Optical waveguide and lamp including same

CROSS-REFERENCE TO RELATED APPLICATIONS

0001The present application claims the benefit of U.S. Provisional U.S. Patent Application No. 61/758,660, filed Jan. 30, 2013, entitled “Optical Waveguide” and further comprises a continuation-in-part of U.S. U.S. patent application Ser. No. 13/842,521, filed Mar. 15, 2013, entitled “Optical Waveguides”, and further comprises a continuation-in-part of U.S. patent application Ser. No. 13/839,949, filed Mar. 15, 2013, entitled “Optical Waveguide and Lamp Including Same”, and further comprises a continuation-in-part of U.S. patent application Ser. No. 13/841,074, filed Mar. 15, 2013, entitled “Optical Waveguide Body”, and further comprises a continuation-in-part of U.S. patent application Ser. No. 13/840,563, filed Mar. 15, 2013, entitled “Optical Waveguide and Luminaire Including Same”, and further comprises a continuation-in-part of U.S. patent application Ser. No. 13/938,877, filed Jul. 10, 2013, entitled “Optical Waveguide and Luminaire Incorporating Same”, all owned by the assignee of the present application, and the disclosures of which are incorporated by reference herein. This patent application also incorporates by reference co-pending U.S. patent application Ser. No. 14/101,086, entitled “Optical Waveguides and Luminaires Incorporating Same” by Eric J. Tarsa et al., filed Dec. 9, 2013, U.S. patent application Ser. No. 14/101,099, entitled “Optical Waveguide Assembly And Light Engine Including Same” by Zongjie Yuan et al., filed Dec. 9, 2013, U.S. patent application Ser. No. 14/101,132, entitled “Waveguide Bodies Including Redirection Features and Methods of Producing Same” by Eric J. Tarsa, filed Dec. 9, 2013, U.S. patent application Ser. No. 14/101,147, entitled “Luminaires Using Waveguide Bodies and Optical Elements” by Bernd Keller et al., filed Dec. 9, 2013, and U.S. patent application Ser. No. 14/101,129 entitled “Simplified Low Profile Module With Light Guide For Pendant, Surface Mount, Wall Mount And Stand Alone Luminaires” by Eric J. Tarsa et al., filed Dec. 9, 2013.

REFERENCE REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

0002Not applicable

SEQUENTIAL LISTING

0003Not applicable

FIELD OF THE INVENTION

0004The present inventive subject matter relates to optical waveguides, and more particularly to optical waveguides for general lighting.

BACKGROUND OF THE INVENTION

0005An optical waveguide mixes and directs light emitted by one or more light sources, such as one or more light emitting diodes (LEDs). A typical optical waveguide includes three main components: one or more coupling elements, one or more distribution elements, and one or more extraction elements. The coupling component(s) direct light into the distribution element(s), and condition the light to interact with the subsequent components. The one or more distribution elements control how light flows through the waveguide and is dependent on the waveguide geometry and material. The extraction element(s) determine how light is removed by controlling where and in what direction the light exits the waveguide.

0006When designing a coupling optic, the primary considerations are: maximizing the efficiency of light transfer from the source into the waveguide; controlling the location of light injected into the waveguide; and controlling the angular distribution of the light in the coupling optic. One way of controlling the spatial and angular spread of injected light is by fitting each source with a dedicated lens. These lenses can be disposed with an air gap between the lens and the coupling optic, or may be manufactured from the same piece of material which defines the waveguide's distribution element(s). Discrete coupling optics allow numerous advantages such as higher efficiency coupling, controlled overlap of light flux from the sources, and angular control of how the injected light interacts with the remaining elements of the waveguide. Discrete coupling optics use refraction, total internal reflection, and surface or volume scattering to control the distribution of light injected into the waveguide.

0007After light has been coupled into the waveguide, it must be guided and conditioned to the locations of extraction. The simplest example is a fiber-optic cable, which is designed to transport light from one end of the cable to another with minimal loss in between. To achieve this, fiber optic cables are only gradually curved and sharp bends in the waveguide are avoided. In accordance with well-known principles of total internal reflectance light traveling through a waveguide is reflected back into the waveguide from an outer surface thereof, provided that the incident light does not exceed a critical angle with respect to the surface.

0008In order for an extraction element to remove light from the waveguide, the light must first contact the feature comprising the element. By appropriately shaping the waveguide surfaces, one can control the flow of light across the extraction feature(s). Specifically, selecting the spacing, shape, and other characteristic(s) of the extraction features affects the appearance of the waveguide, its resulting distribution, and efficiency.

0009Hulse U.S. Pat. No. 5,812,714 discloses a waveguide bend element configured to change a direction of travel of light from a first direction to a second direction. The waveguide bend element includes a collector element that collects light emitted from a light source and directs the light into an input face of the waveguide bend element. Light entering the bend element is reflected internally along an outer surface and exits the element at an output face. The outer surface comprises beveled angular surfaces or a curved surface oriented such that most of the light entering the bend element is internally reflected until the light reaches the output face.

0010Parker et al. U.S. Pat. No. 5,613,751 discloses a light emitting panel assembly that comprises a transparent light emitting panel having a light input surface, a light transition area, and one or more light sources. Light sources are preferably embedded or bonded in the light transition area to eliminate any air gaps, thus reducing light loss and maximizing the emitted light. The light transition area may include reflective and/or refractive surfaces around and behind each light source to reflect and/or refract and focus the light more efficiently through the light transition area into the light input surface of the light emitting panel. A pattern of light extracting deformities, or any change in the shape or geometry of the panel surface, and/or coating that causes a portion of the light to be emitted, may be provided on one or both sides of the panel members. A variable pattern of deformities may break up the light rays such that the internal angle of reflection of a portion of the light rays will be great enough to cause the light rays either to be emitted out of the panel or reflected back through the panel and emitted out of the other side.

0011Shipman U.S. Pat. No. 3,532,871 discloses a combination running light reflector having two light sources, each of which, when illuminated, develops light that is directed onto a polished surface of a projection. The light is reflected onto a cone-shaped reflector. The light is transversely reflected into a main body and impinges on prisms that direct the light out of the main body.

0012Simon U.S. Pat. No. 5,897,201 discloses various embodiments of architectural lighting that is distributed from contained radially collimated light. A quasi-point source develops light that is collimated in a radially outward direction and exit means of distribution optics direct the collimated light out of the optics.

0013Kelly et al. U.S. Pat. No. 8,430,548 discloses light fixtures that use a variety of light sources, such as an incandescent bulb, a fluorescent tube and multiple LEDs. A volumetric diffuser controls the spatial luminance uniformity and angular spread of light from the light fixture. The volumetric diffuser includes one or more regions of volumetric light scattering particles. The volumetric diffuser may be used in conjunction with a waveguide to extract light.

0014Dau et al U.S. Pat. No. 8,506,112 discloses illumination devices having multiple light emitting elements, such as LEDs disposed in a row. A collimating optical element receives light developed by the LEDs and a light guide directs the collimated light from the optical element to an optical extractor, which extracts the light.

0015A.L.P. Lighting Components, Inc. of Niles, Ill., manufactures a waveguide having a wedge shape with a thick end, a narrow end, and two main faces therebetween. Pyramid-shaped extraction features are formed on both main faces. The wedge waveguide is used as an exit sign such that the thick end of the sign is positioned adjacent a ceiling and the narrow end extends downwardly. Light enters the waveguide at the thick end and is directed down and away from the waveguide by the pyramid-shaped extraction features.

0016Low-profile LED-based luminaires have recently been developed (e.g., General Electric's ET series panel troffers) that utilize a string of LED components directed into the edge of a waveguiding element (an “edge-lit” approach). However, such luminaires typically suffer from low efficiency due to losses inherent in coupling light emitted from a predominantly Lambertian emitting source such as a LED component into the narrow edge of a waveguide plane.

0017Van Ostrand et al. U.S. Pat. No. 8,002,450 discloses a light mixing waveguide for edge-lit flat panel displays. The waveguide has a reflectorized edge, a pair of opposing side edges, a light transfer edge opposite the reflectorized edge, and a number of cavities formed inside the waveguide. One of the side edges is configured to receive light from a light source so that the received light is totally-internally reflected from top and bottom surfaces of the waveguide. Interaction of the received light, the cavities, and the reflectorized edge mixes the received light prior to the light passing through the light transfer edge and into a target optical system.

SUMMARY OF THE INVENTION

0018According to one aspect of the present invention, an optical waveguide comprises a body of optically transmissive material defined by outer edges and comprising a width substantially greater than an overall thickness thereof. The body of optically transmissive material comprises a first side and a second side opposite the first side. An interior coupling cavity is defined by a surface intersecting the second side and extends from the second side toward the first side of the body of optically transmissive material and is disposed remote from edges of the body and is configured to receive an LED element. The body of optically transmissive material further comprises a first array of cavities surrounding the interior coupling cavity, an extraction feature disposed on one of the first and second sides wherein the light extraction feature at least partially surrounds the interior coupling cavity, and a total internal reflectance optical member disposed in the interior coupling cavity.

0019According to a second aspect of the present invention, a luminaire comprises a base comprising an electrical connector, a central body disposed on the base, and a light assembly joined to the central body. The light assembly comprises a lightguide body utilizing total internal reflection and comprising an interior coupling cavity, an LED element disposed in the coupling cavity, and a first array of cavities surrounding the coupling cavity. The light assembly further comprises a reflective surface disposed in the interior coupling cavity and the lightguide body is comprised of a material such that the LED element directs light onto the reflective surface and the light is deverted transversely into the material of the lightguide body. Furthermore, the light passes through a cavity of the first array of cavities at an angle that is different from an angle at which the light passes through the material of the lightguide body.

0020According to another aspect of the present invention, an optical waveguide comprises a body of optically transmissive material comprising a width substantially greater than an overall thickness thereof. The body of optically transmissive material comprises a first side, a second side opposite the first side, and an interior coupling cavity extending between the first and second sides. The interior coupling cavity is configured to receive an LED element. The body of optically transmissive material further comprises at least one array of color mixing cavities each extending at least partially through the waveguide body and the array of color mixing cavities surround the interior coupling cavity. Further, the waveguide body utilizes total internal reflection, and the body of optically transmissive material comprises light mixing features in the interior coupling cavity.

0021Other aspects and advantages of the present invention will become apparent upon consideration of the following detailed description and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

<figref idref="DRAWINGS">FIG. 1</figref> is an isometric view of a first end of a first lamp incorporating a waveguide according to a first embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 2</figref> is a first end elevational view of the lamp of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 3</figref> is a side elevational view of the lamp of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 4</figref> is an isometric view of a second end of the lamp of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 5</figref> is a second end elevational view of the lamp of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 6</figref> is an exploded isometric first end view of the lamp of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 7</figref> is an exploded isometric second end view of the lamp of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 8</figref> is a sectional isometric view of the lamp of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 9</figref> is an interior isometric view of the waveguide of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 10</figref> is an interior elevational view of the waveguide of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 11</figref> is a cross sectional view of the waveguide of <figref idref="DRAWINGS">FIG. 1</figref> taken generally along the lines <b>11</b>-<b>11</b> of <figref idref="DRAWINGS">FIG. 10</figref>;

<figref idref="DRAWINGS">FIG. 11A</figref> is a view identical to <figref idref="DRAWINGS">FIG. 11</figref> identifying sample dimensions of the waveguide of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIGS. 11B and 11C</figref> are isometric views of non-circular and asymmetric waveguides, respectively;

<figref idref="DRAWINGS">FIG. 11D</figref> is a diagrammatic elevational view of an asymmetric waveguide;

<figref idref="DRAWINGS">FIGS. 11E and 11F</figref> are cross sectional views taken generally along the lines <b>11</b>E-<b>11</b>E and <b>11</b>F-<b>11</b>F, respectively, of <figref idref="DRAWINGS">FIG. 11D</figref>;

<figref idref="DRAWINGS">FIG. 12</figref> is an isometric view of a first end of a second lamp incorporating a waveguide according to a second embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 13</figref> is a first end elevational view of the lamp of <figref idref="DRAWINGS">FIG. 12</figref>;

<figref idref="DRAWINGS">FIG. 14</figref> is a first side elevational view of the lamp of <figref idref="DRAWINGS">FIG. 12</figref>;

<figref idref="DRAWINGS">FIG. 15</figref> is a second side elevational view of the lamp of <figref idref="DRAWINGS">FIG. 12</figref>;

<figref idref="DRAWINGS">FIG. 16</figref> is a second end isometric view of the lamp of <figref idref="DRAWINGS">FIG. 12</figref>;

<figref idref="DRAWINGS">FIG. 17</figref> is a second end elevational view of the lamp of <figref idref="DRAWINGS">FIG. 12</figref>;

<figref idref="DRAWINGS">FIG. 18</figref> is an exploded isometric first end view of the lamp of <figref idref="DRAWINGS">FIG. 12</figref>;

<figref idref="DRAWINGS">FIGS. 18A and 18B</figref> are isometric views of a further lamp;

<figref idref="DRAWINGS">FIG. 18C</figref> is an exploded isometric view of yet another lamp;

<figref idref="DRAWINGS">FIG. 18D</figref> is a side elevational view of the lamp of <figref idref="DRAWINGS">FIG. 18C</figref> as assembled;

<figref idref="DRAWINGS">FIG. 18E</figref> is a front elevational view of the lamp of <figref idref="DRAWINGS">FIG. 18D</figref>;

<figref idref="DRAWINGS">FIG. 18F</figref> is a bottom elevational view of the lamp of <figref idref="DRAWINGS">FIG. 18D</figref>;

<figref idref="DRAWINGS">FIG. 18G</figref> is a top plan view of the lamp of <figref idref="DRAWINGS">FIG. 18D</figref>;

<figref idref="DRAWINGS">FIGS. 19, 19A and 20-25</figref> are cross sectional views similar to <figref idref="DRAWINGS">FIG. 11</figref> of further embodiments of waveguides according to the present invention;

<figref idref="DRAWINGS">FIGS. 26-29</figref> are elevational views of still further embodiments of waveguides according to the present invention;

<figref idref="DRAWINGS">FIG. 30</figref> is a side elevational view, partly in section, of yet another embodiment of a luminaire including a waveguide according to the present invention;

<figref idref="DRAWINGS">FIG. 31</figref> is a view identical to <figref idref="DRAWINGS">FIG. 11</figref> of a further waveguide according to the present invention;

<figref idref="DRAWINGS">FIG. 32</figref> is a sectional and first side isometric view of the waveguide of <figref idref="DRAWINGS">FIG. 31</figref>;

<figref idref="DRAWINGS">FIG. 33</figref> is a sectional and second side isometric view of the waveguide of <figref idref="DRAWINGS">FIG. 31</figref>;

<figref idref="DRAWINGS">FIG. 34</figref> is a sectional view identical to <figref idref="DRAWINGS">FIG. 31</figref> identifying sample dimensions of the waveguide thereof;

<figref idref="DRAWINGS">FIG. 35</figref> is an enlarged fragmentary view of a portion of the waveguide of <figref idref="DRAWINGS">FIG. 34</figref> seen generally at the lines <b>35</b>-<b>35</b> of <figref idref="DRAWINGS">FIG. 34</figref>;

<figref idref="DRAWINGS">FIGS. 36-38</figref> are isometric, plan and sectional views, respectively, of a further embodiment of an optical waveguide;

<figref idref="DRAWINGS">FIG. 39</figref> is a schematic diagram of a driver circuit suitable for developing power for the LED(s) of <figref idref="DRAWINGS">FIGS. 1-8</figref>;

<figref idref="DRAWINGS">FIGS. 40-42</figref> are isometric, plan, and fragmentary sectional views, respectively, of yet another optical waveguide;

<figref idref="DRAWINGS">FIG. 43</figref> is a side elevational view with portions broken away of a lamp incorporating a waveguide;

<figref idref="DRAWINGS">FIGS. 44A-44D</figref> are a top isometric view, a bottom isometric view, a side elevational view, and a plan view, respectively, of the light assembly of <figref idref="DRAWINGS">FIG. 43</figref>;

<figref idref="DRAWINGS">FIGS. 45A and 45B</figref> are exploded isometric views of the light assembly of <figref idref="DRAWINGS">FIG. 43</figref>;

<figref idref="DRAWINGS">FIG. 45C</figref> is a view similar to <figref idref="DRAWINGS">FIG. 43</figref> illustrating an alternative lamp incorporating a waveguide;

<figref idref="DRAWINGS">FIG. 46</figref> is trimetric view of a further embodiment of an optical waveguide of the present invention;

<figref idref="DRAWINGS">FIG. 46A</figref> is a trimetric view of another embodiment of the waveguide of <figref idref="DRAWINGS">FIG. 46</figref>;

<figref idref="DRAWINGS">FIG. 46B</figref> is a trimetric view of another embodiment of the waveguide of <figref idref="DRAWINGS">FIG. 46</figref>;

<figref idref="DRAWINGS">FIG. 46C</figref> is a trimetric view of another embodiment of the waveguide of <figref idref="DRAWINGS">FIG. 46</figref>;

<figref idref="DRAWINGS">FIG. 47</figref> is a cross sectional view of the waveguide of <figref idref="DRAWINGS">FIG. 46</figref> taken generally along the line <b>47</b>-<b>47</b> of <figref idref="DRAWINGS">FIG. 46</figref>;

<figref idref="DRAWINGS">FIG. 47A</figref> is a cross sectional view of an alternate embodiment of the waveguide of <figref idref="DRAWINGS">FIG. 47</figref>;

<figref idref="DRAWINGS">FIG. 48</figref> is trimetric view of a further embodiment of the optical waveguide of <figref idref="DRAWINGS">FIG. 46</figref>;

<figref idref="DRAWINGS">FIG. 48A</figref> is a trimetric view of another embodiment of the waveguide of <figref idref="DRAWINGS">FIG. 48</figref>;

<figref idref="DRAWINGS">FIG. 48B</figref> is a trimetric view of another embodiment of the waveguide of <figref idref="DRAWINGS">FIG. 48</figref>;

<figref idref="DRAWINGS">FIG. 49</figref> is a plan view of a further embodiment of an optical waveguide;

<figref idref="DRAWINGS">FIG. 50</figref> is a trimetric view of an end of a lamp incorporating the waveguide illustrated in <figref idref="DRAWINGS">FIG. 46</figref>;

<figref idref="DRAWINGS">FIG. 51</figref> is a plan view of the lamp of <figref idref="DRAWINGS">FIG. 50</figref> without a plug member;

<figref idref="DRAWINGS">FIG. 52</figref> is a partial fragmentary diagrammatic view of the waveguide of <figref idref="DRAWINGS">FIG. 12</figref> illustrating the general path light beams emitted from two different light sources travel as the light beams pass through the waveguide;

<figref idref="DRAWINGS">FIG. 52A</figref> illustrates an embodiment in which the LEDs <b>663</b> are disposed in a checkerboard pattern with the red LEDs <b>663</b><i>b </i>being disposed between the blue-shifted LEDs <b>663</b><i>a; </i>

<figref idref="DRAWINGS">FIG. 53</figref> is a partial fragmentary diagrammatic view of the waveguide of <figref idref="DRAWINGS">FIG. 50</figref> illustrating the general path light beams emitted from two different light sources travel as the light beams pass through a first array of cavities and a second array of cavities disposed in the waveguide;

<figref idref="DRAWINGS">FIG. 54</figref> is trimetric view of another embodiment of the waveguide of <figref idref="DRAWINGS">FIG. 46</figref>; and,

<figref idref="DRAWINGS">FIG. 55</figref> is a partial diagrammatic elevational view of another embodiment of the asymmetric waveguide of <figref idref="DRAWINGS">FIG. 11D</figref>.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

0082Referring first to <figref idref="DRAWINGS">FIGS. 1-8</figref>, a lamp <b>40</b> includes a base <b>42</b> at which an Edison-style plug <b>44</b> is disposed. Extending away from the base <b>42</b> is a central body <b>46</b>. Four arms <b>48</b><i>a</i>-<b>48</b><i>d </i>extend away from the central body <b>46</b>. A light assembly <b>50</b> is disposed on ends of the arms <b>48</b><i>a</i>-<b>48</b><i>d </i>and is secured thereto by any suitable means, such as three screws <b>51</b> or other fasteners (shown in <figref idref="DRAWINGS">FIGS. 5 and 7</figref>) that extend through holes in the ends of the arms <b>48</b><i>a</i>-<b>48</b><i>c </i>into threaded bores of the light assembly <b>50</b>.

0083As seen in <figref idref="DRAWINGS">FIGS. 6 and 8</figref>, the light assembly <b>50</b> includes a base element in the form of a heat exchanger <b>52</b> having a central recess <b>54</b> defined by a base surface <b>56</b> and a tapered circumferential wall <b>58</b>. The heat exchanger <b>52</b> is made of any suitable heat conductive material, such as aluminum, and includes a plurality of heat exchanger fins <b>59</b> (<figref idref="DRAWINGS">FIGS. 3-7</figref>) on a side thereof opposite the central recess <b>54</b>. Further, if desired, the base surface <b>56</b> and/or the tapered circumferential wall <b>58</b> may be covered or coated by a reflective material, which may be a white material or a material that exhibits specular reflective characteristics. A light source <b>60</b> that may include one or more light emitting diodes (LEDs) (seen in <figref idref="DRAWINGS">FIG. 8</figref>) is mounted on a support member <b>62</b> comprising a heat conductive substrate, such as a metal circuit board, and extends beyond the base surface <b>56</b>. The LED may be one or more white or other color LED's or may comprise multiple LEDs either mounted separately or together on a single substrate or package including a phosphor-coated LED either alone or in combination with at least one color LED, such as a green LED, a yellow or amber LED, a red LED, etc. In those cases where a soft white illumination is to be produced, the light source <b>60</b> typically includes one or more blue shifted yellow LEDs and one or more red LEDs. Different color temperatures and appearances could be produced using other LED combinations, as is known in the art. In one embodiment, the light source comprises any LED, for example, an MT-G LED incorporating TrueWhite® LED technology or as disclosed in U.S. patent application Ser. No. 13/649,067, filed Oct. 10, 2012, entitled “LED Package with Multiple Element Light Source and Encapsulant Having Planar Surfaces” by Lowes et al., the disclosure of which is hereby incorporated by reference herein, both as developed by Cree, Inc., the assignee of the present application. In any of the embodiments disclosed herein the LED(s) have a particular emission distribution, as necessary or desirable. For example, a side emitting LED disclosed in U.S. Pat. No. 8,541,795, the disclosure of which is incorporated by reference herein, may be utilized inside the waveguide body. More generally, any lambertian, symmetric, wide angle, preferential-sided, or asymmetric beam pattern LED(s) may be used as the light source. Still further, any of the LED arrangements and optical elements disclosed in co-pending U.S. patent application Ser. No. 14/101,147, entitled “Luminaires Using Waveguide Bodies and Optical Elements” by Bernd Keller et al., filed Dec. 9, 2013, incorporated by reference herein, may be used.

0084The light source <b>60</b> is operated by control circuitry <b>64</b> in the form of a driver circuit (seen in <figref idref="DRAWINGS">FIG. 8</figref>) disposed in the central body <b>46</b> that receives AC power via the Edison-style plug. The control circuitry <b>64</b> may be potted within the central body <b>46</b>. Wires or conductors extend through one or more of the arms <b>48</b><i>a</i>-<b>48</b><i>d </i>from the control circuitry <b>64</b> to the light source <b>60</b>. In the illustrated embodiment, wires extend through the arm <b>48</b><i>d </i>into the light assembly <b>50</b>. A cover <b>66</b> (<figref idref="DRAWINGS">FIG. 5</figref>) may be disposed in or over the arm <b>48</b><i>d </i>to provide a passage for the wires. The control circuitry <b>64</b> is designed to operate the light source <b>60</b> with AC or DC power in a desired fashion to produce light of a desired intensity and appearance. The heat exchanger <b>52</b> is preferably arranged to eliminate thermal crosstalk between the LEDs and the control circuitry. Preferably, the light source <b>60</b> develops light appropriate for general illumination purposes including light similar or identical to that provided by an incandescent, halogen, or other lamp that may be incorporated in a down light, a light that produces a wall washing effect, a task light, a troffer, or the like.

0085A waveguide <b>70</b> has a main body of material <b>71</b> (<figref idref="DRAWINGS">FIG. 11</figref>) having a width substantially greater than an overall thickness thereof and is substantially or completely circular in a dimension transverse to the width and thickness (<figref idref="DRAWINGS">FIG. 2</figref>). The waveguide <b>70</b> is disposed in contact with the base surface <b>56</b> and the tapered circumferential wall <b>58</b> and is located by four location pins <b>72</b><i>a</i>-<b>72</b><i>d </i>(<figref idref="DRAWINGS">FIG. 7</figref>) that are disposed in corresponding blind bores <b>74</b><i>a</i>-<b>74</b><i>d </i>(only the bores <b>74</b><i>b</i>-<b>74</b><i>d </i>are visible in <figref idref="DRAWINGS">FIGS. 6 and 8</figref>). In the illustrated embodiment, the waveguide <b>70</b> includes a first or outer side or surface <b>70</b><i>a</i>, a second opposite inner side or surface <b>70</b><i>b</i>, and an interior coupling cavity comprising a central bore <b>76</b> that in the illustrated embodiment extends fully through the waveguide <b>70</b> from the first side to the second side. If desired, the coupling cavity need not extend fully through the waveguide <b>70</b>. Also in the illustrated embodiment, the walls defining the central bore <b>76</b> are normal to the first and second sides <b>71</b><i>a</i>, <b>71</b><i>b </i>of the waveguide <b>70</b> and the central bore <b>76</b> is coaxial with an outer surface of the main body of material <b>71</b>. In all the embodiments disclosed herein, the central bore is preferably polished and optically smooth. Also preferably, the light source <b>60</b> extends into the central bore <b>76</b> from the second side thereof. Also in the illustrated embodiment, a light diverter of any suitable shape and design, such as a conical plug member <b>78</b> extends into the central bore <b>76</b> from the first side thereof. Referring specifically to <figref idref="DRAWINGS">FIGS. 7 and 8</figref>, in the illustrated embodiment, the conical plug member <b>78</b> includes a first portion in the form of a base flange <b>80</b> that is secured by any suitable means, such as an adhesive, to an outer surface of the waveguide <b>70</b> such that a second or conical portion <b>82</b> extends into the central bore <b>76</b>. If desired, the base flange <b>80</b> may be omitted and the outer diameter of the plug member may be slightly greater than the diameter of the bore <b>76</b> whereupon the plug member <b>78</b> may be press fitted or friction fitted into the bore <b>76</b> and/or secured by adhesive or other means. Still further, if desired, the conical plug member <b>78</b> may be integral with the waveguide <b>70</b> (see <figref idref="DRAWINGS">FIG. 47</figref>) rather than being separate therefrom. Further, the light source <b>60</b> may be integral with the waveguide <b>70</b> or encased within the waveguide body <b>71</b>, if desired. In the illustrated embodiment, the plug member <b>78</b> may be made of white polycarbonate or any other suitable material, such as acrylic, molded silicone, polytetrafluoroethylene (PTFE), Delrin® acetyl resin, or any suitable metal. The material may be coated with reflective silver or other metal or material using any suitable application methodology, such as a vapor deposition process. Thus, for example, the plug member <b>78</b> may be coated with silver, aluminum, or another metal in accordance with the teachings of co pending U.S. patent application Ser. No. 14/101,086, entitled “Optical Waveguides and Luminaires Incorporating Same” by Eric J. Tarsa et al., filed Dec. 9, 2013, incorporated by reference herein. The plug member <b>78</b> may be any other suitable shape, including a symmetric or asymmetric shape, a noncircular shape, etc., as desired. For example, the plug member may be non-conical and may have a substantially flat shape, a segmented shape, an inclined shape to direct light out a particular side of the lamp <b>40</b>, etc. The coupling cavity may also (although it need not) have a noncircular shape or the shape may be circular where the first portion <b>80</b> is disposed and secured (in which case the first portion <b>80</b> is circular cylindrical) and the shape of the coupling cavity may be noncircular in other portions (i.e., at locations remote from the first portion <b>80</b>). Specifically, the coupling cavity may be of any shape including, for example, those disclosed in co-pending U.S. patent application Ser. No. 14/101,086, entitled “Optical Waveguides and Luminaires Incorporating Same” by Eric J. Tarsa et al., filed Dec. 9, 2013, incorporated by reference herein to promote mixing of light developed by the light source <b>60</b>.

0086The waveguide <b>70</b> may be secured in any suitable fashion and by any suitable means to the heat exchanger <b>52</b>. In the illustrated embodiment, a ring member <b>90</b> is retained on surfaces of the heat exchanger <b>52</b> such that ribs <b>92</b> of the heat exchanger <b>52</b> are disposed in recesses <b>94</b> of the ring member <b>90</b>. This securement is accomplished by the screws <b>51</b>, which may extend into threaded bosses (not shown) carried on an inner surface of the ring member <b>90</b>. In addition the ring member <b>90</b> bears against that outer surface of the waveguide <b>70</b> so that the waveguide <b>70</b> is secured in place.

0087In the illustrated embodiment the lamp <b>40</b> has a size and outer envelope equivalent to a PAR <b>38</b> lamp, and can be used in any luminaire that can accommodate same. It should be noted that the lamp <b>40</b> could be made larger or smaller to fit inside other luminaires and/or to satisfy particular lighting requirements. One example of a luminaire with which the lamp <b>40</b> could be used is a downlight mounted, for example, in a ceiling. In such a case, the plug <b>44</b> of the lamp <b>40</b> is screwed into an Edison-style socket in the luminaire such that the light source <b>60</b> points downwardly (i.e., the lamp <b>40</b> is oriented opposite to the orientation of <figref idref="DRAWINGS">FIG. 3</figref> such that the plug <b>44</b> is above the waveguide <b>70</b>.) <figref idref="DRAWINGS">FIG. 11</figref> illustrates the waveguide <b>70</b> in such orientation with the light source <b>60</b> disposed above the plug member <b>78</b>. When the light source <b>60</b> is energized, light developed by the source <b>60</b> travels within the bore <b>76</b> and reflects off the surface of the conical portion <b>82</b>. Preferably, the conical portion <b>82</b> is made of or the surface is coated with a white or specular material that is highly reflective such that the great majority of light incident thereon (preferably, although not necessarily, greater than 95%) is reflected into the waveguide <b>70</b> in a generally transverse direction along the width of the body of material <b>71</b>. Examples of such reflected light rays are shown in <figref idref="DRAWINGS">FIG. 11</figref>. Alternatively, the plug member <b>78</b> may be partially or fully transparent or translucent, as desired, to allow at least some light to be transmitted therethrough (for example, at least about 5% of the light may be transmitted through the plug member <b>78</b>). In any event, the spacing, number, size and geometry of extraction features <b>100</b> determine the mixing and distribution of light in the waveguide <b>70</b> and light exiting the waveguide <b>70</b>. In the illustrated embodiment, the extraction features <b>100</b> comprise a series of ridges separated by intervening troughs at least some of which define one or more inverted V-shapes. Also in the illustrated embodiment, the extraction features <b>100</b> are continuous (i.e., they extend fully in a continuous manner about the central bore <b>76</b>), are coaxial with the central bore, and therefore symmetric about the central axis of the central bore <b>76</b>. In addition to the foregoing, the waveguide <b>70</b> is tapered from the center of the waveguide to an outside edge in the sense that there is less material at the radially outside edges of the waveguide than at the center. Such tapering may be effectuated by providing extraction features that become deeper and/or are more widely separated with distance from the center of the waveguide, as noted in greater detail hereinafter. The tapering maximizes the possibility that substantially all the light introduced into the waveguide <b>70</b> is extracted over a single pass of the light through the waveguide. This results in substantially all of the light striking the radially outward surfaces of the extraction features <b>100</b>, which are carefully controlled so that the extraction of light is also carefully controlled. The combination of tapering with the arrangement of extraction features and use of efficient coupling components including the plug member <b>78</b> disposed in the bore <b>76</b> with the light source <b>60</b> together result in improved color mixing with minimum waveguide thickness and excellent control over the emitted light.

0088In the illustrated embodiment, the light emitted out the waveguide <b>70</b> is mixed such that point sources of light in the source <b>60</b> are not visible to a significant extent and the emitted light is controlled and collimated to a high degree.

0089In the illustrated embodiment, the waveguide is made of any suitable optical grade material including one or more of acrylic, air, molded silicone, polycarbonate, glass, and/or cyclic olefin copolymers, and combinations thereof, particularly (although not necessarily) in a layered arrangement to achieve a desired effect and/or appearance. In one example, the waveguide has the dimensions noted in the following table and as seen in <figref idref="DRAWINGS">FIG. 11A</figref>. It should be noted that the dimensions in the following table as exemplary only and not limiting (several of the dimensions are taken with respect to a center line <b>101</b> (<figref idref="DRAWINGS">FIG. 11A</figref>) of the waveguide <b>70</b>):

0090<tables id="TABLE-US-00001" num="00001"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="28pt" align="left" /><colspec colname="1" colwidth="49pt" align="left" /><colspec colname="2" colwidth="140pt" align="center" /><thead><row><entry /><entry namest="offset" nameend="2" rowsep="1">TABLE 1</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row><row><entry /><entry /><entry>NOMINAL DIMENSION</entry></row><row><entry /><entry>REFERENCE</entry><entry>(Millimeters - unless</entry></row><row><entry /><entry>(FIG. 11A)</entry><entry>otherwise specified)</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="28pt" align="left" /><colspec colname="1" colwidth="49pt" align="left" /><colspec colname="2" colwidth="140pt" align="char" char="." /><tbody valign="top"><row><entry /><entry>A</entry><entry>48.500</entry></row><row><entry /><entry>B</entry><entry>43.600</entry></row><row><entry /><entry>C</entry><entry>38.100</entry></row><row><entry /><entry>D</entry><entry>35.100</entry></row><row><entry /><entry>E</entry><entry>33.100</entry></row><row><entry /><entry>F</entry><entry>29.700</entry></row><row><entry /><entry>G</entry><entry>28.700</entry></row><row><entry /><entry>H</entry><entry>25.500</entry></row><row><entry /><entry>I</entry><entry>21.000</entry></row><row><entry /><entry>J</entry><entry>17.000</entry></row><row><entry /><entry>K</entry><entry>12.700</entry></row><row><entry /><entry>L</entry><entry>8.000</entry></row><row><entry /><entry>M</entry><entry>6.000</entry></row><row><entry /><entry>N</entry><entry>5.000</entry></row><row><entry /><entry>P</entry><entry>8.000</entry></row><row><entry /><entry>Q</entry><entry>132.8°</entry></row><row><entry /><entry>R</entry><entry>241.7°</entry></row><row><entry /><entry>S</entry><entry>70.7°</entry></row><row><entry /><entry>T</entry><entry>58.8°</entry></row><row><entry /><entry>U</entry><entry>51.5°</entry></row><row><entry /><entry>V</entry><entry>50.6°</entry></row><row><entry /><entry>W</entry><entry>46.4°</entry></row><row><entry /><entry>X</entry><entry>47.1°</entry></row><row><entry /><entry>Y</entry><entry>56.2°</entry></row><row><entry /><entry>Z</entry><entry>42.3°</entry></row><row><entry /><entry>AA</entry><entry>4.000</entry></row><row><entry /><entry>AB</entry><entry>5.000</entry></row><row><entry /><entry>AC</entry><entry>1.500</entry></row><row><entry /><entry>AD</entry><entry>5.000</entry></row><row><entry /><entry>AE</entry><entry>1.000</entry></row><row><entry /><entry>AF</entry><entry>4.000</entry></row><row><entry /><entry>AG</entry><entry>0.500</entry></row><row><entry /><entry>AH</entry><entry>4.000</entry></row><row><entry /><entry>AI</entry><entry>4.000</entry></row><row><entry /><entry>AJ</entry><entry>4.000</entry></row><row><entry /><entry>AK</entry><entry>4.000</entry></row><row><entry /><entry>AL</entry><entry>2.000</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0091From the foregoing dimensions one can calculate extraction feature aspect ratios as follows: <br />Aspect Ratio=Width of ridge/Greatest height extent of ridge  (1)<br /> Using the foregoing equation, one can calculate (at least approximately) aspect ratios AR1, AR2, and AR3 of various extraction features EF1, EF2, and EF3 denoted in <figref idref="DRAWINGS">FIG. 11A</figref> as follows: <br />AR1=(<i>C−E</i>)/(<i>AB−AC</i>)=(38.1−33.1)/(5.0−1.5)=5.0/3.5=1.43  (2)<br />AR2=(<i>H−I</i>)/<i>AI</i>=(25.5−21.0)/4.0=4.5/4.0=1.125  (3)<br />AR3=(<i>K−L</i>)/<i>AK</i>=(12.7−8.0)/4.0=4.7/4=1.175  (4)

0092In the illustrated embodiment, the waveguide <b>70</b> may be designed to create a beam angle that preferably is between less than about 5 degrees to greater than 60 degrees, and more preferably is between about 5 degrees and about 50 degrees and most preferably between about 6 degrees and about 40 degrees. The beam peak can either be centered in the nadir (as in a PAR application) or off-center (as in an outdoor application). The beam angle and/or peak can be controlled through appropriate design of the waveguide <b>70</b>. In the illustrated embodiment of <figref idref="DRAWINGS">FIG. 11A</figref>, the beam angle is about 12 degrees.

0093In any of the embodiment disclosed herein, the extraction features may be similar or identical to one another in shape, size, and/or pitch, or may be different from one another in any one or more of these parameters, as desired.

0094If desired, the extraction features <b>100</b> may be other than circular, asymmetric and/or discontinuous. <figref idref="DRAWINGS">FIG. 11B</figref> illustrates a racetrack-shaped waveguide <b>70</b><i>a </i>with racetrack-shaped extraction features <b>100</b><i>a</i>. <figref idref="DRAWINGS">FIG. 11C</figref> shows a circular waveguide <b>70</b><i>b </i>with asymmetric and discontinuous extraction features <b>100</b><i>b</i>. An asymmetric plug member <b>78</b><i>a </i>that may be used with the waveguide <b>70</b><i>b </i>is illustrated in <figref idref="DRAWINGS">FIG. 11C</figref>. Asymmetric extraction features may be used with or without an asymmetric plug member to obtain multiple beam distributions. For example, as seen in <figref idref="DRAWINGS">FIG. 11D</figref>, a first set of discrete extraction features <b>100</b><i>b </i>disposed in discrete boundaries <b>100</b><i>b</i>-<b>1</b> through <b>100</b><i>b</i>-<b>6</b> may direct light toward a first direction and at least a second set of extraction features <b>100</b><i>c </i>disposed in discrete boundaries <b>100</b><i>c</i>-<b>1</b> through <b>100</b><i>c</i>-<b>8</b> may direct light toward at least a second direction with each of the at least two directed beams having substantially identical or different beam widths and/or intensities. <figref idref="DRAWINGS">FIGS. 11E and 11F</figref> illustrate different extraction features that may accomplish this result. In a still further example seen in <figref idref="DRAWINGS">FIGS. 36-38</figref>, the extraction features <b>100</b> may comprise a plurality of discrete prisms <b>102</b> formed in a lower surface (as seen in <figref idref="DRAWINGS">FIGS. 33-39</figref>) of a waveguide main body <b>103</b> and arranged in concentric rings. As in the previous embodiment, the light source <b>60</b> and the plug member <b>78</b> extend into an internal cavity <b>76</b>. The waveguide main body <b>103</b> is disposed on a substrate <b>104</b> that may have a reflective coating thereon and light developed by the light source <b>60</b> is diverted transversely into the main body <b>103</b> and is emitted out a surface <b>105</b> by the prisms <b>102</b>. The prisms may be identical or not identical to one another. Preferably, the prisms face the internal cavity <b>76</b>. The prisms <b>102</b> are much smaller in size than the extraction features <b>100</b> of previous and later embodiments and may be of the size(s) specified in co-pending U.S. patent application Ser. No. 14/101,086, entitled “Optical Waveguides and Luminaires Incorporating Same” by Eric J. Tarsa et al., filed Dec. 9, 2013, incorporated by reference herein. Still further, In all of the embodiments disclosed herein, one or more pluralities of light extraction features or elements <b>100</b> may be disposed in one or both upper and lower surfaces of the waveguide body <b>103</b>. Each light extraction feature <b>100</b> may alternatively comprise a facet or other planar or non-planar feature (e.g., a wedge-shaped feature or a curved feature, such as a hemisphere) that is formed by any suitable process, such as embossing, cold rolling, or the like, as disclosed in co-pending U.S. patent application Ser. No. 14/101,086, entitled “Optical Waveguides and Luminaires Incorporating Same” by Eric J. Tarsa et al., filed Dec. 9, 2013, incorporated by reference herein or U.S. patent application Ser. No. 13/842,521 incorporated by reference herein. In any of the embodiments disclosed herein the extraction features <b>100</b> may be disposed in an array such that the extraction features <b>100</b> are disposed at a first density proximate the cavity and gradually increase in density or size with distance from the light source <b>60</b>, as seen in U.S. patent application Ser. No. 13/842,521. Further in any of the embodiments disclosed herein, as seen in <figref idref="DRAWINGS">FIGS. 3A and 3B</figref>, the extraction features may be similar or identical to one another in shape, size, and/or pitch (i.e., spacing), or may be different from one another in any one or more of these parameters, as desired. The features <b>100</b> may comprise indents, depressions, or holes extending into the waveguide, or bumps or facets or steps that rise above the surface of the waveguide, or a combination of both bumps and depressions. Features of the same size may be used, with the density of features increasing with distance from the source, or the density of features may be constant, with the size of the feature increasing with distance from the source (as seen in <figref idref="DRAWINGS">FIG. 36</figref>). For example, where the density of the extraction features is constant with the spacing between features of about 500 microns, and each extraction feature comprises a hemisphere, the diameter of the hemisphere may be no greater than about 1 mm, more preferably no greater than about 750 microns, and most preferably no greater than about 100 microns. Where each extraction feature comprises a shape other than a hemisphere, preferably the greatest dimension (i.e., the overall dimension) of each feature does not exceed about 1 mm, and more preferably does not exceed about 750 microns, and most preferably does not exceed about 100 microns. Also, the waveguide body <b>71</b> may have a uniform or non-uniform thickness. Irrespective of whether the thickness of the waveguide body <b>71</b> is uniform or non-uniform, a ratio of extraction feature depth to waveguide body thickness is preferably between about 1:10,000 and about 1:2, with ratios between about 1:10,000 and about 1:10 being more preferred, and ratios between about 1:1000 and about 1:5 being most preferred.

0095<figref idref="DRAWINGS">FIG. 39</figref> is a schematic diagram of a driver circuit <b>110</b> suitable for developing power for the LED(s) and which may be used as the circuitry <b>64</b>. The driver circuit <b>110</b> is an I²C control that includes an integrated circuit IC <b>112</b>. The IC <b>112</b> and other circuitry operate as a constant current source. The circuit <b>110</b> further includes a full-wave rectifier circuit including diodes D<b>1</b>-D<b>4</b> coupled to a capacitor C<b>1</b> and filter elements comprising inductors L<b>1</b> and L<b>2</b> and a capacitor C<b>2</b>. A diode D<b>5</b> effectuates unidirectional charging of the capacitor C. The circuit <b>110</b> operates as a two-stage regulation circuit that is capable of operating two sets of LEDs <b>113</b><i>a</i>, <b>113</b><i>b </i>in a controllable dimming fashion in response to a dimming command signal SDA delivered to an input of the IC <b>112</b> by a dimmer (not shown). In the illustrated embodiment, each of the LEDs <b>113</b><i>a </i>is capable of developing white light, and each of the LEDs <b>113</b><i>b </i>is capable of producing temperature-compensated red light that adds warmth to the white light developed by the LEDs <b>113</b><i>a</i>. The two sets of LEDs <b>113</b><i>a</i>, <b>113</b><i>b </i>may be disposed on a single substrate or may be disposed on multiple substrates, as desired.

0096Two transistors Q<b>1</b> and Q<b>2</b> implement the two stage regulation circuit and are operated together with a third transistor Q<b>3</b> to control the current through the LEDs <b>113</b>. A diode D<b>6</b> isolates the transistors Q<b>1</b> and Q<b>2</b> from one another. The IC <b>112</b> is also responsive to a signal SCL that is factory set and commands a specific maximum constant current magnitude for the LEDs <b>113</b>. The IC <b>112</b> implements a soft-switching controllable boost and buck converter for dimming of the LED(s) <b>113</b> that produces low electromagnetic interference (EMI) and no 120 Hz. AC component in the DC power that is supplied to the LEDs <b>113</b>.

0097The balance of the circuit <b>110</b> includes a voltage divider including resistors R<b>1</b> and R<b>2</b> wherein a junction between the resistors R<b>1</b> and R<b>2</b> is coupled to an input of the IC <b>112</b>. A thermistor R<b>3</b> is disposed in heat transfer relationship with the LEDs <b>113</b><i>b </i>and provides a thermal sensing signal that is fed back to an input of the IC <b>112</b> whereby the IC <b>112</b> regulates the power delivered to the LEDs <b>113</b><i>b </i>in dependence upon the sensed temperature to effectuate the temperature compensation of the LEDs <b>113</b><i>b</i>. In addition a resistor R<b>4</b> pulls an input of the IC <b>112</b> down when the transistor Q<b>1</b> is off and a resistor R<b>5</b> couples a Power_In input of the IC <b>112</b> to a DC bus <b>116</b>. In the illustrated embodiment, the driver circuit <b>110</b> is mounted on a single circuit board and is compatible with a wide range of dimmers.

0098Any other suitable driver circuit may be used as the circuitry <b>64</b>.

0099Referring next to <figref idref="DRAWINGS">FIGS. 12-18</figref>, a second embodiment of a lamp <b>140</b> is shown. The lamp <b>140</b> is intended for use in luminaires that can accommodate PAR <b>30</b> bulbs. The lamp <b>140</b> includes a base <b>142</b> at which an Edison-style plug <b>144</b> is disposed. Extending away from the base <b>142</b> is a cap <b>145</b> (<figref idref="DRAWINGS">FIG. 18</figref>) and a central body <b>146</b>. The cap <b>145</b> is secured in any suitable fashion to the central body <b>146</b>, such as by ultrasonic welding. Four arms <b>148</b><i>a</i>-<b>148</b><i>d </i>extend away from the central body <b>146</b>. A light assembly <b>150</b> is disposed on ends of the arms <b>148</b><i>a</i>-<b>148</b><i>d </i>and is secured thereto by any suitable means, such as four threaded fasteners <b>151</b><i>a</i>-<b>151</b><i>d </i>that extend through associated bores in associated tabs <b>153</b><i>a</i>-<b>153</b><i>d </i>carried by the central body <b>146</b> and into threaded bores (not seen in the FIGS.) of the light assembly <b>150</b>.

0100As seen in <figref idref="DRAWINGS">FIG. 18</figref>, the light assembly <b>150</b> includes a base element in the form of a heat exchanger <b>152</b> having a central recess <b>154</b> defined by a base surface <b>156</b> and a tapered circumferential wall <b>158</b>. The heat exchanger <b>152</b> is made of any suitable heat conductive material, such as aluminum, and includes a plurality of heat exchanger fins <b>159</b> on a side thereof opposite the central recess <b>154</b>. Further, if desired, and as in the embodiment of <figref idref="DRAWINGS">FIGS. 1-8</figref>, the base surface <b>156</b> and/or the tapered circumferential wall <b>158</b> may be covered or coated by a reflective material, which may be a white material or a material that exhibits specular reflective characteristics. A light source comprising one or more light emitting diodes (LEDs) <b>160</b> that is identical or similar to the light source <b>60</b> seen in <figref idref="DRAWINGS">FIG. 8</figref> is mounted on a support member (not seen, but which may be identical or similar to the member <b>62</b> described above comprising a heat conductive substrate, such as a metal circuit board), and extends beyond the base surface <b>156</b>.

0101The light source <b>160</b> is operated by control circuitry (not shown, but which may be identical or similar to the circuitry <b>64</b> described above) disposed in the central body <b>146</b> that receives AC power via the Edison-style plug. As in the previous embodiment, the control circuitry may be potted in the central body <b>146</b>. Wires or conductors extend through one or more of the arms <b>148</b><i>a</i>-<b>148</b><i>d </i>from the control circuitry to the light source <b>160</b>. As in the previous embodiment, preferably, the light source <b>160</b> develops light appropriate for general illumination purposes.

0102A waveguide <b>170</b> is disposed in contact with the base surface <b>156</b> and the tapered circumferential wall <b>158</b> and is located by four location pins <b>172</b> that are disposed in corresponding blind bores <b>174</b> (the pins and the bores are identical or similar to the pins <b>72</b> and bores of <figref idref="DRAWINGS">FIGS. 6 and 8</figref>). In the illustrated embodiment, the waveguide <b>170</b> is similar or identical to the waveguide <b>70</b> or any other waveguide disclosed herein, it being understood that the waveguide may alternatively be modified in accordance with the design details of the present invention. As in the previous embodiment, the light source <b>160</b> extends into a central bore <b>176</b> of the waveguide <b>170</b> from a second side thereof. Also in the illustrated embodiment, a conical plug member <b>178</b> is secured to the waveguide <b>170</b> by any suitable means, such as a press fit, friction fit, and/or adhesive, and extends into the central bore <b>176</b> from the first side thereof, as in the embodiment of <figref idref="DRAWINGS">FIGS. 1-8</figref>. Also as noted above, the conical plug member <b>178</b> may be integral with the waveguide <b>170</b> rather than being separate therefrom. (For example, see <figref idref="DRAWINGS">FIG. 47</figref>, which illustrates that the plug member may be disposed completely within the central bore.) Further, the light source <b>160</b> may be integral with the waveguide <b>170</b>, if desired.

0103The waveguide <b>170</b> may be secured in any suitable fashion and by any suitable means to the heat exchanger <b>152</b>. In the illustrated embodiment, a ring member <b>190</b> similar or identical to the ring member <b>90</b> is secured to surfaces of the heat exchanger <b>152</b> and is retained thereon such that ribs <b>192</b> of the heat exchanger <b>152</b> are disposed in recesses <b>194</b> of the ring member <b>190</b> (<figref idref="DRAWINGS">FIG. 18</figref>). In addition the ring member <b>190</b> bears against that outer surface of the waveguide <b>170</b> so that the waveguide <b>170</b> is secured in place.

0104As in the previous embodiment, the lamp <b>140</b> can be used for general illumination, such as in a downlight or other luminaire, and achieves the advantages noted with respect to the previous embodiment.

0105<figref idref="DRAWINGS">FIGS. 18A and 18B</figref> show yet another lamp <b>195</b> suitable for general illumination purposes. The lamp <b>195</b> may be of a size suitable for use as a PAR <b>30</b> lamp. The lamp <b>195</b> is substantially similar to the lamp <b>140</b> and includes two main arms <b>196</b><i>a</i>, <b>196</b><i>b </i>secured to a heat exchanger assembly including open fin structures <b>197</b> secured to a lower surface of a light assembly <b>198</b>. The light assembly <b>198</b> includes the waveguide <b>170</b>, or any other suitable waveguide, the light source <b>160</b>, and the plug member <b>178</b> (or any other suitable light source and/or plug assembly). The light source <b>160</b> is mounted on a circuit board substrate that is intimately thermally coupled to the heat exchanger assembly by one or more rings <b>198</b><i>a</i>. Control circuitry (not shown) is disposed within a central body <b>199</b> and is connected to control the light source <b>160</b> by one or more wires that extend though one or both of the arms <b>196</b><i>a</i>, <b>196</b><i>b</i>. The open fin arrangement of the heat exchanger assembly and the intimate thermal coupling of the light source <b>160</b> to the heat exchanger assembly may allow improved thermal management such that the lamp <b>195</b> might be usable in enclosed installations.

0106<figref idref="DRAWINGS">FIGS. 18C-18G</figref> show a still further lamp <b>195</b><i>a </i>suitable for general illumination purposes. The lamp <b>195</b><i>a </i>may be of a size suitable for use as a PAR <b>30</b> lamp. The lamp <b>195</b><i>a </i>is substantially similar to the lamp <b>140</b> and includes three main arms <b>196</b><i>c</i>, <b>196</b><i>d</i>, <b>196</b><i>e </i>carried by a cup-shaped member <b>196</b><i>f </i>and secured to a heat exchanger assembly including open fin structures <b>197</b><i>a </i>secured to a lower surface of a light assembly <b>198</b><i>a</i>. The light assembly <b>198</b><i>a </i>includes the waveguide <b>170</b>, or any other suitable waveguide, the light source <b>160</b>, and the plug member <b>178</b> (or any other suitable light source and/or plug assembly). The light source <b>160</b> is mounted on a circuit board substrate that is intimately thermally coupled to the heat exchanger assembly by one or more rings <b>198</b><i>b</i>. Control circuitry (not shown) is disposed within a central body <b>199</b><i>a </i>and is connected to control the light source <b>160</b> by one or more wires that extend though one or more of the arms <b>196</b><i>c</i>-<b>196</b><i>e</i>. The open fin arrangement of the heat exchanger assembly and the intimate thermal coupling of the light source <b>160</b> to the heat exchanger assembly may allow improved thermal management such that the lamp <b>195</b><i>a </i>might also be usable in enclosed installations.

0107Referring next to <figref idref="DRAWINGS">FIGS. 19-25</figref>, the waveguide can be modified to achieve other visual and/or optical characteristics. Specifically, the size, shape, other geometry, spacing, number, symmetry, and/or other physical characteristic(s) of the waveguide generally and/or the extraction features can be varied, as desired. Thus, <figref idref="DRAWINGS">FIG. 19</figref> illustrates a waveguide <b>202</b> having an axial outer wall <b>203</b> and extraction features <b>204</b> comprising a plurality of ridges and troughs <b>205</b>, <b>206</b>. In this embodiment, the ridges <b>205</b> are unequally spaced, for example, the ridge <b>205</b><i>a </i>is spaced a first distance from an adjacent ridge <b>205</b><i>b</i>, the ridge <b>205</b><i>b </i>is spaced a second, different distance from an adjacent ridge <b>205</b><i>c</i>, and the ridge <b>205</b><i>c </i>is spaced a third distance from an adjacent ridge <b>205</b><i>d</i>. Further, the depths of the troughs <b>206</b> are different. Specifically, a depth of a trough <b>206</b><i>a </i>is different than the depths of troughs <b>206</b><i>b</i>, <b>206</b><i>c </i>and <b>206</b><i>d</i>. The shapes of one or more of the ridges <b>205</b><i>a</i>, <b>205</b><i>b</i>, <b>205</b><i>c</i>, and <b>205</b><i>d </i>can be different than other ridges. Also, a tapered surface <b>207</b><i>a </i>may be disposed at a first angle and a tapered surface <b>207</b><i>b </i>may be disposed at a second angle different than the first angle with respect to the first side of the waveguide. Alternatively, the pitch or spacings between troughs <b>205</b>, the depths of the troughs <b>206</b>, the angles of tapered surfaces <b>207</b>, and the widths and shapes of the troughs <b>206</b> and/or the ridges <b>205</b> may be the same or different, as desired (compare <figref idref="DRAWINGS">FIG. 19</figref> to subsequent FIGS.).

0108It should be also noted that less than all of the ridges <b>205</b> may be coterminous. Thus, for example, as seen in <figref idref="DRAWINGS">FIG. 19A</figref>, a ridge <b>205</b><i>a </i>may be disposed at a different elevation (i.e., distance from the first side of the waveguide) than remaining ridges <b>205</b><i>b</i>, <b>205</b><i>c </i>and/or <b>205</b><i>d</i>, which are coterminous.

0109<figref idref="DRAWINGS">FIG. 20</figref> illustrates a waveguide <b>208</b> having an inclined outer surface <b>209</b> wherein the surface <b>209</b> linearly tapers from a second side or surface <b>210</b> to a first side or surface <b>211</b>. Extraction features comprising a plurality of ridges <b>212</b> and troughs <b>213</b> are equally sized and spaced in a symmetric pattern about a central axis of the waveguide <b>208</b>. <figref idref="DRAWINGS">FIG. 21</figref> illustrates a waveguide <b>214</b> substantially or completely identical to the waveguide <b>208</b>, with the exception that the outer surface <b>209</b> linearly tapers from the surface <b>211</b> to the surface <b>210</b>. As should be evident from an inspection of <figref idref="DRAWINGS">FIGS. 20 and 21</figref>, the outer surface may be disposed at an acute angle with respect to one of the first and second sides of the waveguide and may be disposed at an obtuse angle with respect to another of the first and second sides.

0110<figref idref="DRAWINGS">FIG. 22</figref> illustrates a waveguide <b>215</b> having a frustoconically-shaped first side including a first surface <b>217</b> that is tapered from a central bore <b>218</b> to the outer surface <b>216</b>. The waveguide <b>215</b> includes equally spaced and equally sized ridges <b>219</b> and troughs <b>220</b> and an outer surface <b>216</b> that extends in an axial direction. A waveguide <b>222</b> shown in <figref idref="DRAWINGS">FIG. 23</figref> is substantially or completely identical to the waveguide <b>215</b>, with the exception that the waveguide <b>223</b> is substantially or completely inverted frustoconically shaped in that the first surface <b>223</b> is inversely linearly tapered from an outer surface <b>224</b> to a central bore <b>225</b> as compared to the embodiment of <figref idref="DRAWINGS">FIG. 22</figref>. Thus, the first side of the waveguide may be convex (as in <figref idref="DRAWINGS">FIG. 22</figref>) or concave (as in <figref idref="DRAWINGS">FIG. 23</figref>) at least in part.

0111<figref idref="DRAWINGS">FIG. 24</figref> illustrates a waveguide <b>228</b> having a concave first surface at least in part and which is identical or similar to <figref idref="DRAWINGS">FIG. 23</figref>, with the exception that first and second sides or surfaces <b>229</b>, <b>230</b> are curved. In the illustrated embodiment, the sides or surfaces <b>229</b>, <b>230</b> converge with radial distance from a centerline of the waveguide <b>228</b> resulting in a tapered waveguide, although these surfaces may alternatively diverge or be equally spaced over the radial dimension thereof.

0112<figref idref="DRAWINGS">FIG. 25</figref> illustrates a waveguide <b>232</b> having an axial outer surface <b>233</b>, a first surface <b>234</b> and a second surface <b>235</b> that is generally parallel to the first surface <b>234</b>. However, in the illustrated embodiment of <figref idref="DRAWINGS">FIG. 25</figref>, the plug member <b>78</b> is replaced by a total internal reflectance optical member <b>236</b> that is disposed within a central bore <b>237</b>. The optical member <b>236</b> permits some light to pass from the light source <b>60</b> axially outwardly therethrough, and further reflects remaining light off of one or more surfaces of the optical member <b>236</b> into the waveguide in a transverse direction, as with the previous embodiments. While the embodiment of <figref idref="DRAWINGS">FIG. 25</figref> may result in better efficiency, and may permit use of a smaller diameter waveguide, color mixing of light developed by the light source <b>60</b> may be adversely affected, and hence, the embodiment of <figref idref="DRAWINGS">FIG. 25</figref> is preferably used with a single color light source <b>60</b> rather than one that attempts to duplicate a true-white appearance. Also, the embodiment of <figref idref="DRAWINGS">FIG. 25</figref> may develop enough intensity to obtain a beam angle greater than or equal to 25° and may render the entire lamp simpler and cheaper. However, it may be that the intensity performance of the embodiment of <figref idref="DRAWINGS">FIG. 25</figref> may be insufficient to permit development of an acceptable beam angle of less than 10°.

0113Still further alternate configurations of the waveguide are illustrated in <figref idref="DRAWINGS">FIGS. 26-29</figref>. <figref idref="DRAWINGS">FIG. 26</figref> shows a waveguide <b>240</b> having an overall circular configuration having a plurality of extraction elements <b>242</b> and a star-shaped central bore <b>244</b> that may be substituted for the circular cylindrical bore of the waveguide <b>70</b>. A complementarily-shaped plug member <b>246</b>, which may also have a star shape, may be inserted into and retained within the star-shaped central bore <b>244</b>. The plug number <b>246</b> may have a star-shaped tapered (i.e., conical) member that reflects light generated by a light source <b>60</b>, or may have a circular conical reflective surface, or any other shaped reflective surface, as desired.

0114<figref idref="DRAWINGS">FIG. 27</figref> illustrates an embodiment wherein a generally circular waveguide <b>248</b> includes a plurality of waveguide features <b>250</b> that surround a central axial bore <b>252</b> of circular cylindrical shape. The extraction features <b>250</b> may comprise a series of ridges <b>252</b> and troughs <b>254</b> wherein the ridges and troughs <b>252</b>, <b>254</b> are approximately or substantially flower-shaped or comprise some other shape. The waveguide <b>248</b> may be used with the plug member <b>78</b>, or another plug member as desired.

0115<figref idref="DRAWINGS">FIGS. 28 and 29</figref> illustrate waveguides <b>260</b>, <b>262</b>, respectively, which are approximately or substantially rectangular or square. In the case of the waveguide <b>260</b> the extraction features <b>264</b> comprise ridges separated by intervening troughs <b>266</b> and the ridges and troughs are rectangular or square. Also in the illustrated embodiment of <figref idref="DRAWINGS">FIG. 28</figref>, corners between the sections of the ridges and troughs are sharp and the ridges and troughs surround a circular cylindrical central bore <b>268</b>. The plug member <b>78</b> may be used with the embodiment of <figref idref="DRAWINGS">FIG. 28</figref>, if desired.

0116<figref idref="DRAWINGS">FIG. 29</figref> illustrates an embodiment identical to <figref idref="DRAWINGS">FIG. 28</figref>, with the exception that the corners between adjacent sections of the ridges and troughs <b>264</b>, <b>266</b> are rounded. Again, a circular cylindrical central bore may be provided and the plug number <b>78</b> may be used with the embodiment of <figref idref="DRAWINGS">FIG. 29</figref>.

0117It should be noted that, in an alternative embodiment, the waveguide can be designed to provide a beam angle that has a minimum transverse spread at a particular distance from the waveguide and larger transverse spreads at lesser and greater distances from the waveguide. More particularly, referring to <figref idref="DRAWINGS">FIG. 30</figref>, a lamp <b>340</b> identical to the lamp <b>40</b> and having a waveguide <b>370</b>, which may be similar or identical to any of the waveguides described hereinabove in terms of material composition and overall geometry, may be designed to include extraction features that are preferably, although not necessarily, symmetric about a central axis of the waveguide. The extraction features may be different than the extraction features described above such that light rays emitted at radially outward portions of the waveguide <b>370</b> are directed axially inwardly and downwardly (as seen in <figref idref="DRAWINGS">FIG. 30</figref>), with the magnitude of the angle of inward direction being roughly or substantially proportional to the radial distance of emission of the light ray from the center of the waveguide <b>370</b>. The resulting beam shape is such that a convergence region <b>373</b> is formed at a distance d from the outer surface of the waveguide. Light rays diverge at distances greater than d from the waveguide <b>370</b>. This beam shape permits a trim ring <b>375</b> of an associated luminaire <b>377</b> to have a relatively small diameter aperture <b>379</b> but still have a significantly large illumination area beyond the distance d. The result is a reduction in visible glare because of the shielding effect provided by the trim ring <b>375</b> and a pleasing aesthetic appearance. In general, the size of the aperture <b>379</b> is preferably equal to or smaller than the size of the waveguide of the lamp <b>340</b>, and, more preferably, the cross sectional size of the aperture <b>379</b> relative to the cross sectional size of the waveguide is between about 1:2 to about 1:4. The design of a waveguide that effectuates the foregoing is within the abilities of one of ordinary skill in the art given the disclosure herein.

0118<figref idref="DRAWINGS">FIGS. 31-35</figref> illustrate yet another embodiment of a waveguide <b>370</b> in accordance with the present invention. The waveguide <b>370</b> may be used in place of any of the waveguides disclosed herein, such as the waveguide <b>170</b>. The waveguide <b>370</b> includes four location pins <b>372</b> that are identical to the pins <b>72</b>. In the illustrated embodiment, the light source <b>60</b> extends into a central bore <b>376</b> of the waveguide <b>370</b> from a second side <b>378</b> thereof. Also in the illustrated embodiment, a conical plug member (such as the plug member <b>78</b>) is secured to the waveguide <b>370</b> by any suitable means, such as adhesive, and extends into the central bore <b>376</b> from a first side <b>380</b> thereof, as in the embodiment of <figref idref="DRAWINGS">FIGS. 1-8</figref>. Also as noted above, the conical plug member <b>78</b> may be integral with the waveguide <b>370</b> rather than being separate therefrom. Further, the light source <b>60</b> may be integral with the waveguide <b>370</b>, if desired.

0119Also in the illustrated embodiment, the central bore <b>376</b> is not cylindrical, but instead comprises a tapered bore defined by twelve equally-sized facets <b>384</b>. In the illustrated embodiment in which the waveguide <b>370</b> is made of an acrylic, the taper may be at an angle between about zero degrees and about 8 degrees. In other embodiments in which the waveguide is made of another material, such as polycarbonate or glass, the taper angle maximum may be other than 8 degrees without significantly adversely affecting efficiency. An extraction feature in the form of a groove <b>386</b> extends into the waveguide <b>370</b> from the first side <b>380</b>. An outer tapered portion <b>388</b> includes first and second sections <b>390</b>, <b>392</b> that meet at a junction <b>394</b> (<figref idref="DRAWINGS">FIG. 32</figref>). As in the previous embodiments, the waveguide <b>370</b> is made of optical grade acrylic and/or silicone and, in one example, has the dimensions noted in the following table and as seen in <figref idref="DRAWINGS">FIG. 34</figref>. It should be noted that the dimensions in the following table as exemplary only and not limiting (the dimension CB is the distance of the junction <b>394</b> from the center line <b>396</b> (<figref idref="DRAWINGS">FIG. 34</figref>) of the waveguide <b>370</b>):

0120<tables id="TABLE-US-00002" num="00002"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="28pt" align="left" /><colspec colname="1" colwidth="49pt" align="left" /><colspec colname="2" colwidth="140pt" align="center" /><thead><row><entry /><entry namest="offset" nameend="2" rowsep="1">TABLE 2</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row><row><entry /><entry /><entry>NOMINAL DIMENSION</entry></row><row><entry /><entry>REFERENCE</entry><entry>(Millimeters - unless</entry></row><row><entry /><entry>(FIG. 34)</entry><entry>otherwise specified)</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="28pt" align="left" /><colspec colname="1" colwidth="49pt" align="left" /><colspec colname="2" colwidth="140pt" align="char" char="." /><tbody valign="top"><row><entry /><entry>CA</entry><entry>47.431</entry></row><row><entry /><entry>CB</entry><entry>44.789</entry></row><row><entry /><entry>CC</entry><entry>42.500</entry></row><row><entry /><entry>CD</entry><entry>39.500</entry></row><row><entry /><entry>CE</entry><entry>38.763</entry></row><row><entry /><entry>CF</entry><entry>34.105</entry></row><row><entry /><entry>CG</entry><entry>30.547</entry></row><row><entry /><entry>CH</entry><entry>28.475</entry></row><row><entry /><entry>CI</entry><entry>26.155</entry></row><row><entry /><entry>CJ</entry><entry>22.171</entry></row><row><entry /><entry>CK</entry><entry>18.203</entry></row><row><entry /><entry>CL</entry><entry>14.042</entry></row><row><entry /><entry>CM</entry><entry>11.658</entry></row><row><entry /><entry>CN</entry><entry>9.032</entry></row><row><entry /><entry>CO</entry><entry>7.348</entry></row><row><entry /><entry>CP</entry><entry>6.5000</entry></row><row><entry /><entry>CQ</entry><entry>5.000</entry></row><row><entry /><entry>CR</entry><entry>36.648</entry></row><row><entry /><entry>CS</entry><entry>34.922</entry></row><row><entry /><entry>CT</entry><entry>4.388</entry></row><row><entry /><entry>CU</entry><entry>7.000</entry></row><row><entry /><entry>CV</entry><entry>4.018</entry></row><row><entry /><entry>CW</entry><entry>3.365</entry></row><row><entry /><entry>CX</entry><entry>1.707</entry></row><row><entry /><entry>CY</entry><entry>2.926</entry></row><row><entry /><entry>CZ</entry><entry>3.000</entry></row><row><entry /><entry>DA</entry><entry>2.926</entry></row><row><entry /><entry>DB</entry><entry>2.926</entry></row><row><entry /><entry>DC</entry><entry>4.582</entry></row><row><entry /><entry>DD</entry><entry>5.525</entry></row><row><entry /><entry>DE</entry><entry>6.500</entry></row><row><entry /><entry>DF</entry><entry>47.4°</entry></row><row><entry /><entry>DG</entry><entry>  45°</entry></row><row><entry /><entry>DH</entry><entry>  45°</entry></row><row><entry /><entry>DI</entry><entry>47.3°</entry></row><row><entry /><entry>DJ</entry><entry>45.7°</entry></row><row><entry /><entry>DK</entry><entry>51.3°</entry></row><row><entry /><entry>DL</entry><entry>43.9°</entry></row><row><entry /><entry>DM</entry><entry>45.6°</entry></row><row><entry /><entry>DN</entry><entry>  95°</entry></row><row><entry /><entry>DO</entry><entry>  45°</entry></row><row><entry /><entry>DP</entry><entry>55.8°</entry></row><row><entry /><entry>DQ</entry><entry>134.1° </entry></row><row><entry /><entry>DR</entry><entry>  49°</entry></row><row><entry /><entry>DS</entry><entry>  55°</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0121From the foregoing dimensions one can calculate extraction feature aspect ratios AR4, AR5, and AR6 at least approximately using the same equation (1) above for extraction features EF4, EF5, and EF6 in <figref idref="DRAWINGS">FIGS. 34 and 35</figref> as follows: <br />AR4=(<i>CE−CG</i>)/(<i>CU−CY</i>)=(38.763−30.547)/(7.000−2.926)=8.216/4.074=2.02  (5)<br />AR5=(<i>CI−CJ</i>)/(<i>CU−DB</i>)=(26.155−22.171)/(7.000−2.926)=3.984/4.074=0.98  (6)<br />AR6=(<i>CN−CP</i>)/(<i>CU−DE</i>)=(9.032−6.500)/(7.000−6.500)=2.532/0.500=5.064  (7)

0122As seen in the FIGS. and as calculated above in the equations (2)-(7), the extraction features EF1-EF6 range between aspect ratios of about 0.98 to about 5.064. Preferably, although not necessarily, the present invention contemplates the use of extraction features having aspect ratios that vary between about 0.25 and about 20, and more preferably between about 0.5 and about 10, and most preferably between about 0.75 and about 7.5.

0123An inspection of tables 1 and 2 above also indicates that, overall, the waveguides include extraction features that are deeper with distance from the center line of the waveguide. Thus, for example, as seen in <figref idref="DRAWINGS">FIG. 11A</figref>, the extraction feature dimension AI is less than the dimensions AK-AF, and the latter dimensions are less than the dimensions AE and AB. The same holds true for the extraction features of <figref idref="DRAWINGS">FIG. 34</figref>. In the illustrated embodiments, the depth of the extraction features varies between a minimum in <figref idref="DRAWINGS">FIG. 34</figref> of 0.5 mm to a maximum in <figref idref="DRAWINGS">FIG. 11A</figref> of 5 mm. Extraction feature depths are preferably expressed as a percentage of overall thickness because, in general, the maximum depth of the extraction features is only limited by the structural integrity of the remaining material. Each extraction feature preferably has a depth between about 5% to about 75% of the overall thickness of the waveguide <b>70</b> (the overall thickness is the top to bottom dimension as seen in <figref idref="DRAWINGS">FIGS. 11A and 34</figref> at the wall defining the central bore) and, more preferably, a depth between about 7% and 67% of the overall thickness of the waveguide. Greater extraction feature depths might be achievable using stronger material(s) for the waveguide.

0124Still further, the spacings (i.e., pitch) between adjacent extraction features overall increases with distance from the center line (although not necessarily in every circumstance between adjacent extraction features having small or approximately equal aspect ratios). For example, the distances between ridges of the extraction features of <figref idref="DRAWINGS">FIGS. 11A and 34</figref> are as follows:

0125<tables id="TABLE-US-00003" num="00003"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="28pt" align="left" /><colspec colname="1" colwidth="49pt" align="left" /><colspec colname="2" colwidth="140pt" align="center" /><thead><row><entry /><entry namest="offset" nameend="2" rowsep="1">TABLE 3</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row><row><entry /><entry>REFERENCE</entry><entry>NOMINAL DIMENSION</entry></row><row><entry /><entry>(FIG. 11A)</entry><entry>(Millimeters)</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /><entry>L-M</entry><entry>2.000</entry></row><row><entry /><entry>K-L</entry><entry>4.700</entry></row><row><entry /><entry>J-K</entry><entry>4.300</entry></row><row><entry /><entry>I-J</entry><entry>4.000</entry></row><row><entry /><entry>H-I</entry><entry>4.500</entry></row><row><entry /><entry>F-H</entry><entry>4.200</entry></row><row><entry /><entry>D-F</entry><entry>5.400</entry></row><row><entry /><entry>B-D</entry><entry>8.500</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0126<tables id="TABLE-US-00004" num="00004"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="offset" colwidth="28pt" align="left" /><colspec colname="1" colwidth="49pt" align="left" /><colspec colname="2" colwidth="140pt" align="center" /><thead><row><entry /><entry namest="offset" nameend="2" rowsep="1">TABLE 4</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row><row><entry /><entry>REFERENCE</entry><entry>NOMINAL DIMENSION</entry></row><row><entry /><entry>(FIG. 34)</entry><entry>(Millimeters)</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /><entry>CO-CP</entry><entry>0.848</entry></row><row><entry /><entry>CN-CO</entry><entry>1.684</entry></row><row><entry /><entry>CM-CN</entry><entry>2.626</entry></row><row><entry /><entry>CL-CM</entry><entry>2.384</entry></row><row><entry /><entry>CK-CL</entry><entry>4.161</entry></row><row><entry /><entry>CJ-CK</entry><entry>3.968</entry></row><row><entry /><entry>CI-CJ</entry><entry>3.984</entry></row><row><entry /><entry>CH-CI</entry><entry>2.320</entry></row><row><entry /><entry>CF-CH</entry><entry>5.630</entry></row><row><entry /><entry>CD-CF</entry><entry>5.395</entry></row><row><entry /><entry namest="offset" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0127The spacing between adjacent extraction features may be as small as about 0.7 mm (or less) near the center line of the waveguide and may be 9 mm (or more) at the outer edges of the waveguide.

0128As in the embodiment of the waveguide shown in <figref idref="DRAWINGS">FIGS. 9-11</figref>, the waveguide <b>370</b> of <figref idref="DRAWINGS">FIG. 34</figref> tapers from the center thereof to the edges in the sense that less material is disposed at the edges of the waveguide <b>70</b> than at the center. This fact, in combination with the particular design of the extraction features and the efficient coupling of light into the waveguide result in the improved color mixing, minimized thickness, and excellent control advantages noted above.

0129Referring next to <figref idref="DRAWINGS">FIGS. 40-42</figref>, a waveguide <b>410</b> is identical to the waveguide <b>370</b> with the following exceptions. Multiple lenslets <b>412</b> are arrayed across a surface <b>414</b>. The lenslets <b>412</b> are identical in size and shape and are substantially equally spaced across the surface <b>414</b> inside the extraction feature <b>386</b>, although this not need to be the case. Specifically, the lenslets could be unequally sized and/or spaced and/or shaped. In the illustrated embodiment, the lenslets <b>412</b> are circular in shape (although other shapes could be used, such as a polygonal shape) and convex (as seen in <figref idref="DRAWINGS">FIG. 41</figref>). Some or all of the lenslets <b>412</b> may be concave, if desired. In the preferred embodiment, each lenslet has a preferred range of aspect ratio of diameter to height of at least about 5:1 to about 60:1. In the illustrated embodiment, each lenslet is 0.1 mm in height and 4 mm in diameter and has a smooth exterior surface. In addition, two additional extraction features <b>416</b>, <b>418</b> are provided radially outside the extraction feature <b>386</b>. In the illustrated embodiment, the extraction features <b>416</b>, <b>418</b> extend fully and continuously about the waveguide <b>410</b> and comprise upstanding annular ribs having smooth outer surfaces. The lenslets <b>412</b> and the extraction features <b>416</b>, <b>418</b> contribute to desirable mixing of light and control over the emitted light while not contributing substantially to waveguide thickness.

0130A further lamp <b>500</b> that is shaped externally similar to a standard incandescent PAR <b>30</b> spotlight is illustrated in <figref idref="DRAWINGS">FIGS. 43-45</figref>. As seen in <figref idref="DRAWINGS">FIG. 43</figref>, the lamp <b>500</b> includes a base <b>502</b> including an Edison-style plug <b>504</b>, a central body <b>505</b>, and a cap member <b>506</b> made of light transmissive material, such as optical grade acrylic, polycarbonate, or silicone. A light assembly <b>507</b> is mounted in any suitable fashion within the central body <b>505</b> and is covered by the cap member <b>506</b>. The cap member <b>506</b> is secured to the central body <b>505</b> in any suitable manner, such as adhesive, ultrasonic welding, or the like. The cap member <b>506</b> includes a smooth, curved outer surface <b>508</b>. The outer surface <b>508</b> and/or an inner surface <b>509</b> of the cap member <b>506</b> are preferably, although not necessarily, coated with a material that diffuses light. Referring also to <figref idref="DRAWINGS">FIGS. 44A-44D, 45A, and 45B</figref>, the light assembly <b>507</b> includes a waveguide body <b>510</b> having extraction features <b>511</b> formed in one or both of inner and outer surfaces <b>512</b>, <b>513</b>, respectively, to obtain a waveguide <b>514</b>, as in the previous embodiments. The inner surface <b>510</b> further includes an interior coupling cavity <b>515</b>. Multiple light sources, such as multiple LEDs <b>516</b>, are arranged on a cylindrical carrier <b>517</b> and are inserted into the coupling cavity <b>515</b>. The LEDs receive power via the Edison-style plug <b>504</b> and a driver circuit mounted on one or more circuit boards <b>518</b> disposed in the central body <b>505</b> such that the LEDs <b>516</b> develop light that is directed radially outwardly into the waveguide body <b>510</b>. Because the light developed by the LEDs is directed outwardly in the first instance, there is no need for a light diverter. Further, as seen in <figref idref="DRAWINGS">FIG. 45C</figref>, the waveguide body <b>510</b> may have a curved outer surface <b>513</b>, if desired, to further mimic a conventional incandescent spotlight. The curved outer surface may be coated with a light-diffusing material, although this need not be the case. As also seen in <figref idref="DRAWINGS">FIG. 45C</figref>, the carrier <b>519</b> and the LEDs <b>516</b> may be disposed in a blind bore comprising the coupling cavity <b>515</b> in the waveguide body <b>510</b>, as opposed to the through bore comprising the coupling cavity <b>515</b> of <figref idref="DRAWINGS">FIGS. 43-45B</figref>.

0131Referring again to <figref idref="DRAWINGS">FIGS. 44A-44D, 45A, and 45B</figref>, the lamp <b>500</b> advantageously utilizes the waveguide <b>514</b> to obtain a beam spread of a desired magnitude, for example, 10 degrees to mimic a narrow-beam incandescent spotlight, if desired. Specifically, the cylindrical carrier <b>517</b> includes multiple (in the illustrated embodiment ten) facets <b>519</b><i>a</i>-<b>519</b><i>j </i>(<figref idref="DRAWINGS">FIGS. 44A</figref> and <b>44</b>D) wherein two or another number of LEDs are mounted in each of the facets <b>519</b>. The extraction features <b>511</b> in the inner surface <b>512</b> of the waveguide body <b>510</b> arrayed in an overall flower-shaped pattern including multiple sections <b>511</b><i>a</i>-<b>511</b><i>j </i>each associated with one of the facets <b>519</b><i>a</i>-<b>519</b><i>j</i>, respectively. Each section <b>511</b><i>a</i>-<b>511</b><i>j </i>is disposed outside of the associated facet <b>519</b><i>a</i>-<b>519</b><i>j </i>and includes nested curved extraction subsections (see, for example, subsections <b>551</b><i>f</i>-<b>1</b>, <b>511</b><i>fa</i>-<b>2</b>, . . . <b>511</b><i>f</i>-N in <figref idref="DRAWINGS">FIG. 45B</figref>). The extraction subsections meet adjacent extraction subsections at inflection regions (see, e.g., inflection regions <b>520</b><i>a</i>, <b>520</b><i>b</i>, . . . , <b>520</b>N in <figref idref="DRAWINGS">FIG. 45B</figref>). Also in the illustrated embodiment, a light extraction feature <b>521</b> comprising groove sections <b>521</b><i>a</i>-<b>521</b><i>j </i>(<figref idref="DRAWINGS">FIG. 44D</figref>) are disposed in the outer surface <b>513</b>. In the illustrated embodiment, each extraction subsection of each section <b>511</b> is coaxial with the LEDs carried by the associated facet <b>519</b>. Light is extracted efficiently out of the waveguide body <b>510</b> by the curved subsections and the groove sections.

0132The waveguide body <b>510</b> and the carrier <b>517</b> with LEDs <b>516</b> are disposed within a reflecting backplane member <b>522</b> having a tapered surface <b>524</b> and a planar base surface <b>526</b>. One or both of the interior surfaces are coated/covered with a reflective material, such as a specular reflective material or film or a white material or film. Light that escapes the inner surface <b>511</b> of the waveguide body <b>510</b> is thus reflected back into the waveguide body so that light is efficiently extracted out the outer surface <b>513</b>. By suitably designing the extraction features that results in a tapered waveguide body <b>510</b> similar to the previous embodiments, one can obtain color mixing and light emission control as in the previous embodiments without utilizing a light diverter, such as the plug member <b>78</b>.

0133It should be noted that any of the embodiments disclosed herein may utilize a reflective backplane member like the member <b>522</b>, if desired. Also, the backplane <b>522</b> may have other than a planar base surface <b>526</b>, such as a curved surface.

0134As seen in <figref idref="DRAWINGS">FIG. 45C</figref>, a heat exchanger <b>528</b> (diagrammatically shown) may be provided in thermal contact with the LEDs and may be disposed immediately below the backplane <b>522</b>. The heat exchanger <b>528</b> can be arranged to eliminate thermal crosstalk between the LEDs and the driver circuit.

0135If desired, the waveguide body <b>510</b> can be modified to obtain a different beam spread, such as greater than 10 degrees. For example, the lamp may achieve a beam spread of 15 degrees, 25 degrees, or even up to 60 degrees, or any value in between.

0136While a uniform distribution of light may be desired in certain embodiments, other distributions of light may be contemplated and obtained using different arrays of extraction features.

0137Another embodiment of a waveguide body <b>670</b> comprised of an optically transmissive material <b>671</b> is shown in <figref idref="DRAWINGS">FIGS. 46-48B and 50-54</figref>. A number of LEDs of the same color together comprising an LED element may be used with the waveguide body <b>670</b>. Alternatively, a number of LEDs not all of the same color and together comprising a multi-color LED element may be used in order to achieve a desired lighting effect, such as a particular color temperature. In the former case, a non-uniform intensity of light may be produced. In the latter case, a multi-color LED element may be subject to non-uniform color distribution at high angles, leading to non-uniformity in the color and intensity of output luminance. A non-uniform color distribution also may result from a multi-color LED element having different color LEDs with varying heights. For example, a multi-color LED element may include one or more red LEDs surrounded by a plurality of blue-shifted yellow LEDs. Each red LED has a height that is less than a height of the surrounding blue-shifted yellow LEDs. The light emitted from the red LED, therefore, is obstructed at least in part by the blue-shifted yellow LED, such that the light emanating from the LED element is not uniform. In addition to height differences, differences in the nature of the red and blue-shifted yellow LEDs affect the way the light is emitted from the respective LED.

0138The waveguide body <b>670</b> is identical to the waveguide body <b>170</b>, discussed above with respect to <figref idref="DRAWINGS">FIGS. 12-18</figref>, with the exception that the waveguide body <b>670</b> includes light redirection feature(s) in the form of one or more cavities <b>602</b> to promote luminance uniformity and, if multi-colored LEDs are used, color mixing. According to an aspect of the present invention, the cavities <b>602</b> may have any of a number of geometries defined by surfaces that promote redirection of the light rays (e.g., through refraction) to improve luminance uniformity and to mix the light rays developed by the LEDs in an improved manner.

0139As shown in <figref idref="DRAWINGS">FIG. 46</figref>, waveguide body <b>670</b> includes a first array of cavities <b>600</b> and a second array of cavities <b>610</b>. As used herein, the term cavity may mean a void that is filled with air or a void that is partially or fully filled with another optically transmissive material such as acrylic, polycarbonate, molded silicone, glass, or cyclic olefin copolymers and/or combinations thereof. The waveguide body <b>670</b> includes an interior coupling cavity <b>676</b> and may include an extraction feature, for example, the extraction feature <b>601</b> (see <figref idref="DRAWINGS">FIG. 47A</figref>). The first array of cavities <b>600</b> surrounds the interior coupling cavity <b>676</b> such that the interior coupling cavity <b>676</b> is disposed, for example, in the center of the first array of cavities <b>600</b> or may be disposed off-center. Although two arrays are shown, in the example embodiments of <figref idref="DRAWINGS">FIGS. 46, 46A, 46B, and 46C</figref>, either a single or more than two arrays of cavities are contemplated. For example, <figref idref="DRAWINGS">FIGS. 48, 48A, and 48B</figref> show an embodiment of waveguide <b>670</b> having a third array of cavities <b>620</b>. Also, each array may partially surround the interior coupling cavity <b>676</b>, as opposed to fully surrounding the interior coupling cavity <b>676</b>. Each array may include as little as one cavity or as many cavities as desired, and the cavities of an array may be equally spaced about the interior coupling cavity <b>676</b> or may be unequally spaced. Still further, the cavities of each array may all have the same shape (e.g., circular cylindrical) or may be of two or more different shapes, and may all be of the same size (e.g., diameter) or may be of two or more different sizes.

0140The first array of cavities <b>600</b> includes a plurality of cavities <b>602</b><i>a</i>, <b>602</b><i>b</i>, . . . , <b>602</b>N. The first array of cavities <b>600</b> may have between 2 and 200 cavities <b>602</b>. Preferably, the first array of cavities <b>600</b> includes between 4 and 60 cavities <b>602</b>, for example. In the illustrated embodiment of <figref idref="DRAWINGS">FIG. 46</figref>, each cavity <b>602</b> of the first array of cavities <b>600</b> preferably is circular-cylindrical in shape and each preferably has a diameter or other cross-sectional dimension of between about 0.3 mm and about 6 mm, for example. More preferably, the diameter or other cross-sectional dimension of each of the cavities <b>602</b> of the first array of cavities <b>600</b> is between about 0.4 mm and about 5 mm and most preferably is between about 0.4 mm and about 4 mm. Each of the cavities <b>602</b> may have a symmetric or asymmetric shape, and may be a shape other than circular-cylindrical, such as star-shaped (<figref idref="DRAWINGS">FIG. 46B</figref>) or elliptical (<figref idref="DRAWINGS">FIG. 46C</figref>). The cavities <b>602</b> may extend fully through the material <b>671</b> of the waveguide body <b>670</b> as shown in <figref idref="DRAWINGS">FIG. 47</figref>. Alternatively, the cavities <b>602</b> may be blind cavities as shown in <figref idref="DRAWINGS">FIG. 47A</figref> such that they only pass partially through the waveguide material <b>671</b>. Further, the cavities <b>602</b> may be arranged in a symmetric circular pattern around the interior cavity as shown in <figref idref="DRAWINGS">FIGS. 46-46C, 50, and 51</figref>, or they may be arranged in a different pattern (not shown), for example, a pattern that is rectangular, triangular, or flower-shaped. Further, the cavities <b>602</b> may be arranged in a symmetric or asymmetric pattern.

0141The second array of cavities <b>610</b> surrounds the first array of cavities <b>600</b> as shown in <figref idref="DRAWINGS">FIG. 46</figref>. The second array of cavities <b>610</b> includes a plurality of cavities <b>612</b><i>a</i>, <b>612</b><i>b</i>, . . . , <b>612</b>N. The second array of cavities <b>610</b> may have between 2 and 200 cavities <b>602</b>. Preferably, the second array of cavities <b>610</b> includes between 6 and 100 cavities <b>612</b>, for example. The cavities <b>612</b> of the second array of cavities <b>610</b> may be angularly offset from the cavities <b>602</b> of the first array of cavities <b>600</b> such that each cavity <b>612</b> is disposed midway between adjacent cavities <b>602</b> of the first array of cavities <b>600</b>. As before, the cavities <b>612</b> may extend fully through the material <b>671</b> of the waveguide body <b>670</b> or may be blind cavities such that they do not pass fully through the waveguide material <b>671</b>.

0142In the illustrated embodiment of <figref idref="DRAWINGS">FIG. 46</figref>, each cavity <b>612</b> is circular-cylindrical in shape. Again, the cavities <b>612</b> may be a shape other than circular-cylindrical, such as star-shaped (<figref idref="DRAWINGS">FIG. 46B</figref>) or elliptical (<figref idref="DRAWINGS">FIG. 46C</figref>). Preferably, although not necessarily, each cavity <b>612</b> of the second array of cavities <b>610</b> has a size (i.e., diameter or other cross-sectional dimension) that is larger than the size of the cavities <b>602</b> of the first array of cavities <b>600</b>. The cavities <b>612</b> of the second array of cavities <b>610</b> may have a diameter or other cross-sectional dimension of between about 0.4 mm and about 10 mm. More preferably, the diameter or other cross-sectional dimension of each of the cavities <b>612</b> of the second array of cavities <b>610</b> is, for example, between about 0.4 mm and about 8 mm and most preferably each diameter or other cross-sectional dimension is between about 0.4 mm and about 10 mm. While the cavities <b>612</b> of the second array of cavities <b>610</b> in the illustrated embodiment have the same shape as the cavities <b>602</b> of the first array of cavities <b>600</b>, e.g., a circular-cylindrical shape (<figref idref="DRAWINGS">FIG. 46</figref>), the cavities <b>612</b> may have a different shape such as a square or rectangular-cylindrical shape as shown in <figref idref="DRAWINGS">FIG. 46A</figref>. Further, the cavities <b>612</b> of the second array of cavities <b>610</b> may be arranged in the same pattern, e.g., the circular pattern as shown in <figref idref="DRAWINGS">FIGS. 46-46C, 50, and 51</figref>, as the cavities <b>602</b> of the first array of cavities <b>600</b>, and/or may be coaxial therewith or they may be arranged in a pattern that is different from and/or not coaxial with respect to the first array of cavities.

0143Another embodiment of the waveguide body <b>670</b> is shown in <figref idref="DRAWINGS">FIGS. 48, 48A, and 48B</figref>. In the illustrated embodiments, the waveguide body includes a third array of cavities <b>620</b>. The third array of cavities <b>620</b> surrounds the second array of cavities <b>610</b>. The third array of cavities <b>620</b> includes a plurality of cavities <b>622</b><i>a</i>, <b>622</b><i>b</i>, . . . , <b>622</b>N. The third array of cavities <b>620</b> may have between 2 and 200 cavities <b>622</b>. The cavities <b>622</b> of the third array of cavities <b>620</b> are angularly offset from the cavities <b>612</b> of the second array of cavities <b>610</b> such that each cavity <b>622</b> is disposed midway between adjacent cavities <b>612</b> of the second array of cavities <b>610</b>. The cavities <b>622</b> may extend fully through the material <b>671</b> of the waveguide body <b>670</b> or may be blind cavities such that they do not pass fully through the waveguide material <b>671</b>.

0144As illustrated in <figref idref="DRAWINGS">FIG. 48</figref>, each cavity <b>622</b> of the third array of cavities <b>620</b> may be circular-cylindrical in shape and may have a size that is larger than the size of the cavities <b>602</b> and <b>612</b> of the first and second array of cavities <b>600</b> and <b>610</b>, respectively. The cavities <b>622</b> also may be a shape other than circular-cylindrical, such as star-shaped (<figref idref="DRAWINGS">FIG. 48A</figref>) or elliptical (<figref idref="DRAWINGS">FIG. 48B</figref>). The cavities <b>622</b> of the third array of cavities <b>620</b> preferably have a diameter or other cross-sectional dimension of between about 0.4 mm and about 10 mm, and more preferably have a diameter or other cross-sectional dimension of between about 1 mm and about 10 mm, and most preferably have a diameter or other cross-sectional dimension between about 2 mm and about 10 mm. While the cavities <b>622</b> of the third array of cavities <b>620</b> in the illustrated embodiment may have the same shape as the cavities <b>602</b> and <b>612</b> of the first and second arrays of cavities <b>600</b> and <b>610</b>, respectively, e.g., a circular-cylindrical shape (<figref idref="DRAWINGS">FIG. 48</figref>), the cavities <b>622</b> of the third array <b>620</b> may also have a different shape, such as a square or rectangular-cylindrical shape (similar or identical to the second array of the embodiment of <figref idref="DRAWINGS">FIG. 46A</figref>). Further, the cavities <b>622</b> of the third array of cavities <b>620</b> may be arranged in the same pattern, e.g., the circular pattern shown in <figref idref="DRAWINGS">FIGS. 48, 48A, and 48B</figref>, as the cavities <b>602</b> and <b>612</b> of the first and second array of cavities <b>600</b> and <b>610</b>, respectively, and/or may be coaxial therewith, or they may be arranged in a pattern that is different from and/or not coaxial with respect to the first and second arrays of cavities (not shown). Further arrays of cavities may be disposed anywhere in the waveguide body <b>670</b> as desired, for example, disposed radially outwardly from the third array of cavities <b>620</b> in any array shape and with cavity shapes and sizes as described hereinabove, or any other shape(s) and/or size(s).

0145Another embodiment of the waveguide body <b>670</b> is shown in <figref idref="DRAWINGS">FIG. 54</figref>. In this embodiment, the waveguide body includes at least one cavity <b>632</b><i>a</i>. Additional cavities <b>632</b><i>b</i>, <b>632</b><i>c</i>, . . . , <b>632</b>N may also be included. The cavities <b>632</b> may be of the same shape (e.g., <b>632</b><i>a </i>and <b>632</b><i>b</i>) or they may be different shapes (e.g., <b>632</b><i>b </i>and <b>632</b><i>c</i>). The shapes of the cavities <b>632</b> may be, for example, circular-cylindrical (i.e., <b>632</b><i>a</i>), elliptical (i.e., <b>632</b><i>d</i>), star-shaped (i.e., <b>632</b><i>c</i>), or any other shape. The cavities <b>632</b> may extend all the way through the material <b>671</b> or may extend only partially through the material <b>671</b>. The cavities may also be of the same or similar size (e.g., <b>632</b><i>a </i>and <b>632</b><i>f</i>) or they may be of different sizes (e.g., <b>632</b><i>a </i>and <b>632</b><i>b</i>). The cavities <b>632</b> may be disposed in the waveguide <b>670</b> in a pattern or they may be disposed in the waveguide at random positions as shown in <figref idref="DRAWINGS">FIG. 54</figref>.

0146Another embodiment of a waveguide body <b>703</b> is shown in <figref idref="DRAWINGS">FIG. 49</figref>. In this embodiment, the waveguide body <b>703</b> is rectangular in shape as compared to the waveguide body <b>670</b>, which is circular in shape. The waveguide body <b>703</b> is identical to waveguide body <b>103</b> as discussed above with respect to <figref idref="DRAWINGS">FIGS. 36-39</figref>, with the exception that waveguide body <b>703</b> includes light redirection feature(s) in the form of one or more cavities <b>702</b>. As shown in <figref idref="DRAWINGS">FIG. 49</figref>, the waveguide body <b>703</b> includes a first array of cavities <b>700</b> and a second array of cavities <b>710</b>. In the illustrated embodiment, the first array of cavities <b>700</b> surrounds an interior coupling cavity <b>776</b>, such that the interior coupling cavity <b>776</b> is disposed in the center of the first array of cavities <b>700</b>.

0147The first array of cavities <b>700</b> includes a plurality of cavities <b>702</b><i>a</i>, <b>702</b><i>b</i>, . . . , <b>702</b>N, and the second array of cavities <b>710</b> includes a plurality of cavities <b>712</b><i>a</i>, <b>712</b><i>b</i>, . . . , <b>712</b>N. The second array of cavities <b>710</b> surrounds the first array of cavities <b>700</b>. The cavities <b>712</b> of the second array of cavities <b>710</b> are angularly offset from the cavities <b>702</b> of the first array of cavities <b>700</b> such that each cavity <b>712</b> is disposed midway between adjacent cavities <b>702</b>, although this need not be the case. Further, the cavities <b>702</b> of the first array of cavities <b>700</b> may be of the same or different size, shape, pattern, number, and material as discussed with respect to cavities <b>602</b> discussed above. Similarly, the cavities <b>712</b> of the second array of cavities <b>710</b> may be of the same or different size, shape, pattern, number, and material as cavities <b>612</b> discussed above.

0148Another embodiment of a waveguide body <b>870</b> comprised of an optically transmissive material <b>871</b> is shown in <figref idref="DRAWINGS">FIG. 55</figref>. As shown in <figref idref="DRAWINGS">FIG. 55</figref>, the waveguide body <b>870</b> is identical to the waveguide discussed above with respect to <figref idref="DRAWINGS">FIGS. 11D-11F</figref>, with the exception that the waveguide body <b>870</b> includes an interior coupling cavity <b>876</b> and one or more light redirection feature(s) in the form of at least one cavity <b>800</b><i>a</i>. Additional cavities <b>800</b><i>b</i>, <b>800</b><i>c</i>, . . . , <b>800</b>N may also be included. The cavities <b>800</b> may be of the same shape (e.g., <b>800</b><i>a </i>and <b>800</b><i>b</i>) or they may be of different shapes. The shapes of the cavities <b>800</b> may be, for example, circular-cylindrical (i.e., <b>800</b><i>a</i>), elliptical, or star-shaped. The cavities may also be of the same or similar size (e.g., <b>800</b><i>b </i>and <b>800</b><i>c</i>) or they may be of different sizes (e.g., <b>800</b><i>a </i>and <b>800</b><i>b</i>). The cavities <b>800</b> may extend all the way through the material <b>871</b> or they may extend only partially through the material <b>871</b>. The cavities <b>800</b> may be disposed on the waveguide <b>870</b> in a specific pattern as shown in <figref idref="DRAWINGS">FIG. 55</figref> or they may be disposed on the waveguide <b>870</b> at random positions.

0149As best shown in <figref idref="DRAWINGS">FIGS. 49 and 51</figref>, the interior coupling cavities <b>676</b> and <b>776</b> of the waveguide bodies <b>670</b> and <b>703</b>, respectively, are configured to receive a light source <b>660</b>. As noted above, the light source <b>660</b> may be an LED module <b>662</b> that includes a number of individual LEDs <b>663</b>. For example, there may be anywhere from one to nine or more individual LEDs <b>663</b> on the LED module <b>662</b>, and the LEDs <b>663</b> may be arranged in any configuration. The LED module <b>662</b>, for example, may include nine individual LEDs <b>663</b> arranged in a 3×3 array as shown in <figref idref="DRAWINGS">FIGS. 51-53</figref>. The LED's <b>663</b> may be blue-shifted yellow LEDs <b>663</b><i>a</i>, red LEDs <b>663</b><i>b</i>, and/or green LEDs (not shown). The LED module <b>662</b> may include six blue-shifted yellow LEDs <b>663</b><i>a </i>and three red LEDs <b>663</b><i>b </i>as shown in <figref idref="DRAWINGS">FIG. 52</figref> or the LED module <b>662</b> may include five blue-shifted yellow LEDs <b>663</b><i>a </i>and four red LEDs <b>663</b><i>b </i>arranged in a checkerboard pattern as shown in <figref idref="DRAWINGS">FIG. 52A</figref>.

0150Referring next to <figref idref="DRAWINGS">FIGS. 50 and 51</figref>, an embodiment of a lamp <b>640</b> is shown. The lamp <b>640</b> is identical to the lamp <b>140</b> except that the lamp <b>640</b> includes the waveguide <b>670</b>. As shown in <figref idref="DRAWINGS">FIG. 50</figref>, the lamp <b>640</b> includes a base <b>642</b> at which an Edison-style plug <b>644</b> is disposed. Extending away from the base <b>642</b> is a central body <b>646</b> to which a light assembly <b>650</b> is secured. The light assembly <b>650</b> includes the light source <b>660</b> (discussed above and similar or identical to the light source <b>60</b>) disposed in the interior coupling cavity <b>676</b> of the waveguide <b>670</b> (<figref idref="DRAWINGS">FIG. 51</figref>). A plug member <b>678</b> identical to plug member <b>68</b> may be inserted into the interior coupling cavity <b>676</b>. The remaining components of lamp <b>140</b> are present but not shown in <figref idref="DRAWINGS">FIGS. 50 and 51</figref>.

0151In <figref idref="DRAWINGS">FIG. 52</figref>, an example of a waveguide <b>670</b> is shown having LED module <b>662</b> with six blue-shifted yellow LEDs <b>663</b><i>a</i>-<b>1</b> through <b>663</b><i>a</i>-<b>6</b> arranged in two rows of three LEDs and three red LEDs <b>663</b><i>b</i>-<b>1</b> through <b>663</b><i>b</i>-<b>3</b> arranged in a single row between the two rows of blue-shifted yellow LEDs on a substrate. The blue-shifted yellow LED <b>663</b><i>a</i>-<b>1</b> emits light beams <b>609</b><i>a </i>and the red LED <b>663</b><i>b</i>-<b>1</b> emits light beams <b>609</b><i>b</i>. The light beams <b>609</b><i>a </i>and <b>609</b><i>b </i>strike the reflective surface of the plug member <b>678</b> and are reflected transversely toward the waveguide <b>670</b>. Alternatively, light from the LEDs <b>663</b><i>a</i>-<b>1</b> and <b>663</b><i>b</i>-<b>1</b> (and other LEDs) directly enter the waveguide <b>670</b>. When the light beams <b>609</b><i>a </i>and <b>609</b><i>b </i>strike the material <b>671</b> of the waveguide <b>670</b>, the light beams <b>609</b><i>a </i>and <b>609</b><i>b </i>refract at an angle α. The light beams <b>609</b><i>a </i>and <b>609</b><i>b </i>travel at the angle α in a Section A until the light beams <b>609</b><i>a </i>and <b>609</b><i>b </i>reach an extraction element such as the extraction feature <b>601</b>. As shown diagrammatically in <figref idref="DRAWINGS">FIG. 52</figref>, as the light beams <b>609</b><i>a </i>and <b>609</b><i>b </i>travel through Section A, the light beams <b>609</b><i>a </i>of the blue-shifted yellow LED <b>663</b><i>a</i>-<b>1</b> cross paths or “mix” with the light beams <b>609</b><i>b </i>of the red LED <b>663</b><i>b</i>-<b>1</b>. However, when the light beams strike the extraction feature <b>601</b>, the directional paths of the light beams <b>609</b><i>a </i>and <b>609</b><i>b </i>change such that a high degree of color separation results.

0152In <figref idref="DRAWINGS">FIG. 53</figref>, a waveguide <b>670</b> having first and second arrays of cavities <b>600</b> and <b>610</b>, respectively, is shown. The same LED module <b>662</b> with blue-shifted yellow LEDs <b>663</b><i>a </i>and red LEDs <b>663</b><i>b </i>that is shown in <figref idref="DRAWINGS">FIG. 52</figref> is included in <figref idref="DRAWINGS">FIG. 53</figref>. Similar to the example shown in <figref idref="DRAWINGS">FIG. 52</figref>, when the light beams <b>609</b><i>a </i>of the blue-shifted yellow LED <b>633</b><i>a</i>-<b>1</b> and the light beams <b>609</b><i>b </i>of the red LED <b>663</b><i>b</i>-<b>1</b> strike the material <b>671</b> of the waveguide <b>670</b>, the light beams initially refract at angle α. However, when either the light beams <b>609</b><i>a </i>or the light beams <b>609</b><i>b </i>strike the cavity <b>602</b> of the first array of cavities <b>600</b>, the light beams <b>609</b> either reflect away from cavity <b>602</b> or refract at an angle β. The light beams <b>609</b><i>a </i>or <b>609</b><i>b </i>that are not reflected travel through the cavity <b>602</b> at the angle β until the light beams reach a point X. When the light beams <b>609</b><i>a </i>or <b>609</b><i>b </i>reach a point X of the cavity <b>602</b>, the light beams either reflect back into the cavity <b>602</b> or refract at an angle θ as the light beams <b>609</b><i>a </i>or <b>609</b><i>b </i>reenter the waveguide material <b>671</b>. Similarly, when either the light beams <b>609</b><i>a </i>or the light beams <b>609</b><i>b </i>strike the cavity <b>612</b> of the second array of cavities <b>610</b>, the light beams either reflect away from cavity <b>612</b> or refract at an angle β₁. If the light beams <b>609</b><i>a </i>or <b>609</b><i>b </i>are not initially reflected, then the light beams pass through cavity <b>612</b> until the light beams <b>609</b><i>a </i>or <b>609</b><i>b </i>reach a point Y. When the light beams <b>609</b><i>a </i>or <b>609</b><i>b </i>reach the point Y of the cavity <b>612</b>, the light beams either reflect back into the cavity <b>612</b> or refract at an angle θ₁as the light beams reenter the waveguide material <b>671</b>.

0153By changing the refraction angles of a light beam over the same area, e.g., Section A, of the waveguide, the light beams are scattered to promote overall luminance uniformity and such that a larger number of blue-shifted yellow light beams <b>609</b><i>a </i>and red light beams <b>609</b><i>b </i>mix in Section A and continue to mix after the light beams <b>609</b><i>a </i>and <b>609</b><i>b </i>strike the extraction feature <b>601</b>. Increasing the amount of luminance uniformity and, in the case of multi-color LED elements, color mixing is desirable because such mixing reduces the appearance of the individual colors of the LEDs <b>663</b><i>a </i>and <b>663</b><i>b </i>and produces a more uniform resultant color, e.g., a warm white light. Further, by providing different sized cavities <b>602</b> and <b>612</b>, the angles at which the light beams <b>609</b><i>a </i>and <b>609</b><i>b </i>of the blue-shifted yellow LEDs <b>663</b><i>a </i>and the red LEDs <b>633</b><i>b</i>, respectively, enter and exit the cavities <b>602</b> and <b>612</b> are greatly varied. This increases the amount of light beam scattering, which further promotes luminance uniformity and color mixing.

0154Each light redirection feature preferably has an overall length in the direction extending radially away from the center of the coupling cavity of no less than about 0.5 mm, and more preferably such overall length is between about 1 mm and about 10 mm, and most preferably between about 2 mm and about 8 mm. Further, each light redirection feature preferably has an overall circumferential extent (or peripheral extent in the event the light redirection feature is noncircular) of no less than about 1 mm, and more preferably between about 4 mm and about 30 mm, and most preferably between about 5 mm and about 20 mm.

0155It should be noted that the placement of LEDs on the substrate can be modified to enhance color mixing. For example, the red LEDs <b>663</b><i>b </i>may be reduced in number to two LEDs while maintaining the same number and arrangement of blue-shifted yellow LEDs. Alternatively, the blue shifted yellow LEDs <b>663</b><i>a </i>may be rearranged to comprise first and second single LEDs disposed adjacent first and second edges or sides of the substrate and first and second pairs of LEDs disposed adjacent the third and fourth sides of the substrate. Two red LEDs <b>663</b><i>b </i>are disposed between the LEDs <b>663</b><i>a </i>optionally remote from the edges of the substrate. Such designs are disclosed in co-pending U.S. patent application Ser. No. 14/101,147, entitled “Luminaires Using Waveguide Bodies and Optical Elements” by Bernd Keller et al., filed Dec. 9, 2013, the disclosure of which is incorporated herein.

0156In addition to the foregoing, a primary or secondary lens of the LED element may be used in conjunction with the LED light source <b>60</b> or <b>660</b> to further improve the luminance and/or color uniformity of the light emitted from the surface of the waveguide. In particular, the shape of the primary LED light source lens may be varied and optimized to use refraction or scattering to direct light into preferred directions prior to entering the coupling cavity, thereby improving uniformity. The orientation and/or shape of the LED element relative to the surface(s) defining the coupling cavity may also be varied and optimized to improve light mixing. The lens and/or any of the waveguides disclosed herein may be formed with one or more materials in accordance with the teachings of either U.S. patent application Ser. No. 13/843,928, filed Mar. 15, 2013, entitled “Multi-Layer Polymeric Lens and Unitary Optic Member for LED Light Fixtures and Method of Manufacture” by Craig Raleigh et al., or U.S. patent application Ser. No. 13/843,649, filed Mar. 15, 2013, entitled “One-Piece Multi-Lens Optical Member and Method of Manufacture” by Craig Raleigh et al., the disclosures of which are hereby incorporated by reference herein. If desired, a scatterer, which may be effectuated by scattering particles coated on or formed within the lens, may be provided to further mix the light developed by the LEDs.

0157Other embodiments of the disclosure including all of the possible different and various combinations of the individual features of each of the foregoing embodiments and examples are specifically included herein. Thus, for example, a waveguide of one of the disclosed shapes may include extraction features of the same or a different shape, and the extraction features may be symmetric or asymmetric, the extraction features may have differing or the same geometry, spacing, size, etc. without departing from the scope of the invention. Also, any of the light redirection features disclosed herein may also function as a light extraction feature, if desired.

0158In any of the embodiments disclosed herein, gaps or interfaces between waveguide elements (such as between the waveguide body and material disposed in a cavity or cavities) may be filled with an optical coupling gel or a different optical element or material, such as an air gap or any of the other materials disclosed herein, or an index matching material. Further, one or more other light redirection feature shapes oriented in any desired direction could be used, wherein the shapes include, for example, V-shaped, elliptical, circular, diamond-shaped, kite-shaped (i.e., a diamond shape with different angles at opposing ends of the shape), rectangular, polygonal, curved, flat, tapered, segmented, continuous, discontinuous, symmetric, asymmetric, etc. The light redirection feature preferably has an overall radial length of no less than about 1 um, and more preferably the overall radial length is between about 10 um and about 10 mm, and most preferably between about 1 mm and about 10 mm. Further the light redirection feature preferably has an overall circumferential (or other overall) extent of no less than about 1 um, and more preferably the overall extent is between about 10 um and about 10 mm, and most preferably between about 1 mm and about 10 mm. Any or all of the surfaces partially or fully defining any or all of the features disclosed herein, including the light redirection features disclosed herein, or any portion thereof, may be coated or otherwise formed with optically reflective materials, such as a specular material, such as a metallized coating, a scattering material, a white material, or the like, if desired.

0159It should be noted that the number, size, and arrangement of the light redirection features may be such as to gradually collimate light over the extent of the waveguide body and/or could cause redirection of light for another purpose, for example, to cause the light to avoid features that would otherwise absorb or scatter such light.

INDUSTRIAL APPLICABILITY

0160In summary, it has been found that when using a single color or multicolor LED element in a luminaire, it is desirable to mix the light output developed by the LEDs thoroughly so that the intensity and/or color appearance emitted by the luminaire is uniform. When the LED element is used with a waveguide, opportunities have been found to exist to accomplish such mixing during the light coupling and light guiding or distributing functions. Specifically, bending the light rays by diffraction can result in improvement in mixing. In such a case, this refractive bending can be accomplished by providing interfaces in the waveguide between materials having different indices of refraction. These interfaces may define light redirection features at portions intermediate light coupling features and waveguide extraction features or areas where light is otherwise extracted (such as by bends) from the waveguide. It has further been found that directing light into a wide range of refraction angles enhances light mixing. Because the angle A_rof a refracted light ray is a function of the angle A_ibetween the incident light ray and the interface surface struck by the incident light ray (with refractive angle A_rincreasing as A_iapproaches zero, i.e., when the incident light ray approaches a parallel condition with respect to the interface surface), a wide range of refracted light ray angles can be obtained by configuring the interface surfaces to include a wide range of angles relative to the incident light rays. This, in turn, means that the interfaces could include a significant extent of interface surfaces that are nearly parallel to the incident light rays, as well as other surfaces disposed at other angles to the incident light rays. Overall waveguide shapes and coupling feature and redirection feature shapes such as curved (including convex, concave, and combinations of convex and concave surfaces), planar, non-planar, tapered, segmented, continuous or discontinuous surfaces, regular or irregular shaped surfaces, symmetric or asymmetric shapes, etc. can be used, it being understood that, in general, light mixing (consistent with the necessary control over light extraction) may be further improved by providing an increased number of interface surfaces and/or more complex interface shapes in the light path. Also, the spacing of coupling features and light redirection features may affect the degree of mixing. In some embodiments a single light coupling feature and/or a single light redirection feature may be sufficient to accomplish a desired degree of light mixing. In other embodiments, multiple coupling features and/or multiple light redirection features might be used to realize a desired degree of mixing. In either event, the shapes of multiple coupling features or multiple redirection features may be simple or complex, they may be the same shape or of different shapes, they may be equally or unequally spaced, or distributed randomly or in one or more arrays (which may themselves be equally or unequally spaced, the same or different size and/or shape, etc.). Further, the interfaces may be disposed in a symmetric or asymmetric pattern in the waveguide, the waveguide itself may be symmetric or asymmetric, the waveguide may develop a light distribution that is symmetric, asymmetric, centered or non-centered with respect to the waveguide, the light distribution may be on-axis (i.e., normal to a face of the waveguide) or off-axis (i.e., other than normal with respect to the waveguide face), single or split-beam, etc.

0161Still further, one or more coupling features or redirection features, or both, may be disposed anywhere inside the waveguide, at any outside surface of the waveguide, such as an edge surface or major face of the waveguide, and/or at locations extending over more than one surface or portion of the waveguide. Where a coupling or light redirection feature is disposed inside the waveguide, the feature may be disposed in or be defined by a cavity extending fully through the waveguide or in or by a cavity that does not extend fully through the waveguide (e.g., in a blind bore or in a cavity fully enclosed by the material of the waveguide). Also, the waveguide of any of the embodiments disclosed herein may be planar, non-planar, irregular-shaped, curved, other shapes, suspended, a lay-in or surface mount waveguide, etc.

0162While specific coupling feature and light redirection feature parameters including shapes, sizes, locations, orientations relative to a light source, materials, etc. are disclosed as embodiments herein, the present invention is not limited to the disclosed embodiments, inasmuch as various combinations and all permutations of such parameters are also specifically contemplated herein. Thus, any one of the coupling cavities, plug members, LED elements, masking element(s), redirection features, extraction features, etc. as described herein may be used in a luminaire, either alone or in combination with one or more additional elements, or in varying combination(s) to obtain light mixing and/or a desired light output distribution. More specifically, any of the features described and/or claimed in U.S. patent application Ser. No. 13/842,521, filed Mar. 15, 2013, entitled “Optical Waveguides” by Kurt S. Wilcox et al., U.S. patent application Ser. No. 13/839,949, filed Mar. 15, 2013, entitled “Optical Waveguide and Lamp Including Same” by Zongjie Yuan et al., U.S. patent application Ser. No. 13/841,074, filed Mar. 15, 2013, entitled “Optical Waveguide Body” by John W. Durkee, U.S. patent application Ser. No. 13/840,563, filed Mar. 15, 2013, entitled “Optical Waveguide and Luminaire Incorporating Same” by Zongjie Yuan et al., U.S. patent application Ser. No. 14/101,086, filed Dec. 9, 2013, entitled “Optical Waveguides and Luminaires Incorporating Same” by Bernd P. Keller et al., U.S. patent application Ser. No. 14/101,132, filed Dec. 9, 2013, entitled “Waveguide Bodies Including Redirection Features and Methods of Producing Same”, U.S. patent application Ser. No. 14/101,147, filed Dec. 9, 2013, entitled “Luminaires Using Waveguide Bodies and Optical Elements” by Bernd P. Keller et al., and U.S. patent application Ser. No. 14/101,129, filed Dec. 9, 2013, entitled “Simplified Low Profile Module with Light Guide For Pendant, Surface Mount, Wall Mount and Stand Alone Luminaires” by Eric J. Tarsa et al., incorporated by reference herein and owned by the assignee of the present application may be used in the devices disclosed herein. Thus, for example, any of the waveguides or luminaires disclosed herein may include one or more coupling features or optics, a modified LED arrangement, one or more light redirection features, one or more light extraction features, and/or particular waveguide or overall luminaire shapes and/or configurations as disclosed in such applications, as necessary or desirable. Other luminaire and waveguide form factors than those disclosed herein are also contemplated.

0163The coupling features disclosed herein efficiently couple light into the waveguide, and the redirection features uniformly mix light within the waveguide and the light is thus conditioned for uniform extraction out of the waveguide. At least some of the luminaires disclosed herein are particularly adapted for use in installations, such as, replacement or retrofit lamps (e.g., LED PAR bulbs), outdoor products (e.g., streetlights, high-bay lights, canopy lights), and indoor products (e.g., downlights, troffers, a lay-in or drop-in application, a surface mount application onto a wall or ceiling, etc.) preferably requiring a total luminaire output of at least about 800 lumens or greater, and, more preferably, a total luminaire output of at least about 3000 lumens, and most preferably a total lumen output of about 10,000 lumens. Further, the luminaires disclosed herein preferably have a color temperature of between about 2500 degrees Kelvin and about 6200 degrees Kelvin, and more preferably between about 2500 degrees Kelvin and about 5000 degrees Kelvin, and most preferably about 2700 degrees Kelvin. Also, at least some of the luminaires disclosed herein preferably exhibit an efficacy of at least about 100 lumens per watt, and more preferably at least about 120 lumens per watt, and further exhibit a coupling efficiency of at least about 92 percent. Further, at least some of the luminaires disclosed herein preferably exhibit an overall efficiency (i.e., light extracted out of the waveguide divided by light injected into the waveguide) of at least about 85 percent. A color rendition index (CRI) of at least about 80 is preferably attained by at least some of the luminaires disclosed herein, with a CRI of at least about 88 being more preferable. A gamut area index (GAI) of at least about 65 is achievable as is a thermal loss of less than about 10%. Any desired form factor and particular output light distribution, such as a butterfly light distribution, could be achieved, including up and down light distributions or up only or down only distributions, etc.

0164When one uses a relatively small light source which emits into a broad (e.g., Lambertian) angular distribution (common for LED-based light sources), the conservation of etendue, as generally understood in the art, requires an optical system having a large emission area to achieve a narrow (collimated) angular light distribution. In the case of parabolic reflectors, a large optic is thus generally required to achieve high levels of collimation. In order to achieve a large emission area in a more compact design, the prior art has relied on the use of Fresnel lenses, which utilize refractive optical surfaces to direct and collimate the light. Fresnel lenses, however, are generally planar in nature, and are therefore not well suited to re-directing high-angle light emitted by the source, leading to a loss in optical efficiency. In contrast, in the present invention, light is coupled into the optic, where primarily TIR is used for re-direction and collimation. This coupling allows the full range of angular emission from the source, including high-angle light, to be re-directed and collimated, resulting in higher optical efficiency in a more compact form factor.

0165Embodiments disclosed herein are capable of complying with improved operational standards as compared to the prior art as follows:

0166<tables id="TABLE-US-00005" num="00005"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="70pt" align="left" /><colspec colname="2" colwidth="49pt" align="center" /><colspec colname="3" colwidth="98pt" align="left" /><thead><row><entry namest="1" nameend="3" align="center" rowsep="1" /></row><row><entry /><entry>State of the Art</entry><entry>Improved Standards Achievable</entry></row><row><entry /><entry>Standards</entry><entry>by Present Embodiments</entry></row><row><entry namest="1" nameend="3" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="70pt" align="left" /><colspec colname="2" colwidth="49pt" align="char" char="." /><colspec colname="3" colwidth="98pt" align="left" /><tbody valign="top"><row><entry>Input coupling</entry><entry>90%</entry><entry>About 95% plus improvements</entry></row><row><entry>efficiency (coupling +</entry><entry /><entry>through color mixing, source</entry></row><row><entry>waveguide)</entry><entry /><entry>mixing, and control within</entry></row><row><entry /><entry /><entry>the waveguide</entry></row><row><entry>Output efficiency</entry><entry>90%</entry><entry>About 95%: improved through</entry></row><row><entry>(extraction)</entry><entry /><entry>extraction efficiency plus</entry></row><row><entry /><entry /><entry>controlled distribution of</entry></row><row><entry /><entry /><entry>light from the waveguide</entry></row><row><entry>Total system</entry><entry>~80%</entry><entry>About 90%: great control,</entry></row><row><entry /><entry /><entry>many choices of output</entry></row><row><entry /><entry /><entry>distribution</entry></row><row><entry namest="1" nameend="3" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0167In at least some of the present embodiments the distribution and direction of light within the waveguide is better known, and hence, light is controlled and extracted in a more controlled fashion. In standard optical waveguides, light bounces back and forth through the waveguide. In the present embodiments, light is extracted as much as possible over one pass through the waveguide to minimize losses.

0168In some embodiments, one may wish to control the light rays such that at least some of the rays are collimated, but in the same or other embodiments, one may also wish to control other or all of the light rays to increase the angular dispersion thereof so that such light is not collimated. In some embodiments, one might wish to collimate to narrow ranges, while in other cases, one might wish to undertake the opposite.

0169All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

0170The use of the terms “a” and “an” and “the” and similar references in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

0171Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the invention.